WO2020012266A1

WO2020012266A1 - Biocatalytic synthesis of olodanrigan (ema401) from 3-(2-(benzyloxy)-3-methoxyphenyl)propenoic acid with phenylalanine ammonia lyase

Info

Publication number: WO2020012266A1
Application number: PCT/IB2019/054995
Authority: WO
Inventors: Feng Gao; Leo Albert HARDEGGER; Roger HUMAIR; Florian Karl KLEINBECK-RINIKER; Florian Andreas Rampf; Thomas Ruch; Thierry Schlama; Bernhard Wietfeld
Original assignee: Novartis Ag
Priority date: 2018-07-12
Filing date: 2019-06-14
Publication date: 2020-01-16

Abstract

The present invention relates to a first biocatalytic process for preparing olodanrigan ((S)-5-(benzyloxy)-2-(2,2-diphenylacetyl)-6- methoxy-l,2,3,4-tetrahydroisoquinoline-3-carboxylic acid; compound of formula (I); EMA401, PD 126055 ) by reacting 3-(2-(benzyloxy) -3-methoxyphenyl)propenoic acid (compound of formula (C3)) with an engineered phenylalanine ammonia lyase (PAL) and an amino donor to (S)-2-amino-3-(2-(benzyloxy)-3-methoxyphenyl)propanoic acid (compound of formula (C4)), and then reacting the compound of formula (C4) to olodanrigan, or a salt, or a solvate thereof. The present invention also relates to a second biocatalytic p rocess for preparing olodanrigan by reacting the compound of formula (C3) with an engineered phenylalanine ammonia lyase (PAL) and an amino donor, and then adding an aldehyde derivative to form (S)-5- (benzyloxy)-6-methoxy-l,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (compound of formula (C5)), and then reacting the compound of formula (C5) to olodanrigan, or a salt, or a solvate thereof. The present invention further relates to a process for preparing pharmaceuticals and pharmaceutical compositions from the compound of formula (I), or a salt, or a solvate thereof. Olodanrigan is used in the treatment of neuropathic and inflammatory pain.

Description

BIOCATALYTIC SYNTHESIS OF OLODANRIGAN (EMA401 ) FROM 3-(2-(BENZYLOXY)-3-METHOXYPHENYL)PROPENOIC ACID WITH

PHENYLALANINE AMMONIA LYASE

FIELD OF THE DISCLOSURE

The present invention relates to processes, process steps and intermediates useful in the preparation of tetrahydroisoquinoline derivatives and their derivatives. In particular, the present invention is in the field of organic synthesis and biocatalytic synthesis and is directed to a method of synthesizing a compound of formula (I), also referred to as (S)-5-(benzyloxy)-2-(2,2- diphenylacetyl)-6-methoxy-1 ,2,3,4-tetrahydroisoquinoline-3-carboxylic acid, or a salt, or a solvate thereof, and/or intermediates thereof, methods for further preparing pharmaceuticals and pharmaceutical compositions from the compound of formula (I), or a salt, or a solvate thereof, or from the intermediates.

REFERENCE TO SEQUENCE LISTING, TABLE OR COMPUTER PROGRAM

The official copy of the Sequence Listing is submitted concurrently with the specification, with a file name of“PAT058187-WO-PCT03_ST25.txt”, a creation date of February 28, 2019 and a size of 44 KB. The Sequence Listing is part of the specification and incorporated in its entirety by reference herein.

BACKGROUND OF THE DISCLOSURE

The present disclosure relates to a process for the preparation of tetrahydroisoquinoline derivatives and their derivatives. More particularly, the present disclosure relates to a process for the preparation of the compound of formula (I)

(I), or a salt, or a solvate thereof.

Also referred to as (S)-5-(benzyloxy)-2-(2,2-diphenylacetyl)-6-methoxy-1 ,2,3,4-tetrahydro isoquinoline-3-carboxylic acid, or a salt, or a solvate thereof. Compound of formula (I) is also known as (S)-2-(Diphenylacetyl)-1 ,2,3,4-tetrahydro-6-methoxy-5-(phenylmethoxy)-3- isoquinolinecarboxylic acid, as EMA401 , or as PD 126055 also known as olodanrigan. The preparation of the compound of formula (I) is disclosed in US 5,246,943. The use of EMA401 for the treatment of neuropathic pain is disclosed in W02006/066361 and its use in treating inflammatory pain is disclosed in W02007/106938. Salts and solvates, inter alia the sodium salt of EMA401 , are described in WO2012/010843.

The compound of formula (I), or a salt, or a solvate thereof, was prepared in US 5,246,943, in 6 steps from commercially available 2-benzyloxy-3-methoxybenzaldehyde. One of the drawbacks observed with this synthesis, was the poor regio- and enantio-selectivity of the direct amine addition in alpha of the carboxylic acid substituent. To overcome this problem an undirected route using a masked amine (the imidozolidine derivative in Examples 3 and 6) was found. Unfortunately, the synthesis proved low yielding (between 13 to 54% yield were obtained at each step), thus not suitable for a large scale manufacturing.

Phenylalanine ammonia lyase (PAL) is a non-mammalian enzyme class that is widely distributed in plants and has also been identified in fungi and a limited number of bacteria. It is normally a tetramer with a typical mass of 300 to 340 kDa (e.g., Cui et al Crit. Rev. Biotechnol. 2014, 34, 258-268). PAL (e.g., Cui et al Crit. Rev. Biotechnol. 2014, 34, 258-268; Hyun et al Mycobiol. 2011 , 39, 257-265; MacDonald et al. Biochem. Cell Biol. 2007, 85, 273-282) along with histidine ammonia lyase (HAL), and tyrosine ammonia lyase (TAL) (e.g., Kyndt et al FEBS Lett. 2002, 512, 240-244; Watt et al Chem. Biol. 2006, 13, 1317; and Xu e et al. J. Ind. Microbiol. Biotechnol. 2007, 34, 599-604) are members of the aromatic amino acid lyase family (EC 4.3.1.23-1.25 and 4.3.1.3). More specifically, the enzymes having PAL activity (EC 4.3.1.23-1.25 and previously classified as EC 4.3.1.5) catalyze the amination of (£)-cinnamic acid into L-phenylalanine. Unfortunately, commercial PALs proved not suitable to improve the regio- and enantio- selectivity of the amine addition.

Thus, there is a need to design and use engineered PALs that can produce chiral amine compounds from a diverse range of substrates, and in particular, for preparing the intermediates of the olodanrigan synthesis. The present disclosure is directed to a synthesis of compound of formula (I), or a salt, or a solvate thereof, and its intermediates, generating less by-products, providing a reproducible process that is easier to handle on a larger scale, which is a process making advantage of engineered PALs to provide the desired intermediates.

SUMMARY OF THE DISCLOSURE

Chemical processes are usually carried out on a small scale in a research / early development phase, and the scale successively increases in late phase development to finally reach the full size production scale. Upon scaling up a process, topics related to process safety are becoming more and more important. Failure to scale up properly may lead to the loss of process control and accidents, such as unexpected exothermic reactions (runaway reactions), health hazards while handling large amount of hazardous and/or toxic chemicals or environmental hazards. Surprisingly it was found that the process to synthesize compound of formula (I), (S)-2- (diphenylacetyl)-1 ,2,3,4-tetrahydro-6-methoxy-5-(phenylmethoxy)-3-isoquinoline-carboxylic acid, or a salt, or a solvate thereof, and the intermediates thereof, can be prepared with a cost efficient and higher yielding route, while controlling the enantioselectivity and regioselectivity of the amine addition, thus reducing the amount of by-products. Therefore, the present disclosure is directed to a new synthesis of compound of formula (I) and its intermediates, generating less waste and providing a reproducible process that is easier to handle on a larger scale, using engineered PALs to obtain the desired amine with high regio-/enantio-selectivity.

In one aspect the invention provides a process for preparing a compound of formula (C4), or a salt thereof, as disclosed herein,

the process comprising the steps of reacting a compound of formula (C3),

salt thereof,

with an engineered phenylalanine ammonia lyase (PAL), and an amino donor, optionally in the presence of a solvent to provide a compound of formula (C4)

salt thereof.

In another aspect the invention provides a process for preparing a compound of formula (C5), or a salt thereof, as disclosed herein, the process comprising the steps of

i. reacting a compound of formula (C3)

salt thereof,

with an engineered phenylalanine ammonia lyase (PAL), and an amino donor, optionally in the presence of a solvent, as defined herein, adding an acid, and then adding an aldehyde derivative, to obtain a compound of formula (C5)

salt, or a solvate thereof.

In another aspect the invention provides a process for preparing a compound of formula (I),

salt, or a solvate thereof,

the process comprising the steps of:

i. reacting a compound of formula (C3), or a salt thereof, to prepare a compound of formula (C4), or a salt thereof, as defined herein

ii. further reacting the compound of formula (C4), or a salt thereof, to obtain a compound of formula (I), or a salt, or a solvate thereof.

In another aspect of the invention provides for a process for preparing a compound of formula (I),

salt, or a solvate thereof,

the process comprising the steps of:

i. reacting a compound of formula (C3), or a salt thereof, to prepare a compound of formula (C5), or a salt thereof, as disclosed herein,

ii. further reacting the compound of formula (C5), or a salt or a solvate thereof, to obtain a compound of formula (I), or a salt, or a solvate thereof. In another aspect the invention provides for a process for preparing a pharmaceutical composition, the process comprising the process as disclosed herein, and mixing the obtained compound of formula (I), or a salt, or a solvate thereof, with a pharmaceutically acceptable excipient.

DETAILED DESCRIPTION OF THE DISCLOSURE

Increasing the amount of reactants and solvents in order to scale up a process to a full size commercial production may be associated with lower yields, or some risk and safety issues while handling large amount of hazardous and/or toxic chemicals.

Surprisingly, it was found a process to synthesize compound of formula (I), or a salt, or a solvate thereof, and the synthetic intermediates in a way as disclosed herein provides a scalable method that can safely be handled on a larger scale, with reproducible yields, providing the amine addition with high regio-/enantio-selectivity using engineered PALs, thus producing less waste. A summary of the overall process is shown in Scheme 1 , vide infra, wherein LG is a leaving group.

The first aspect of the present disclosure relates to a process for preparing a compound of formula (C4), or a salt thereof, as outlined in Scheme 2 below, the process comprising the steps of reacting a compound of formula (C3), or salt thereof, with an engineered phenylalanine ammonia lyase (PAL), and an amino donor, optionally in the presence of a solvent to provide a compound of formula (C4), or salt thereof.

Scheme 2

The amino donor used to perform the reaction as outlined in Scheme 2 is a molecule capable of providing an amino group to an amine acceptor using an engineered phenylalanine ammonia lyase (PAL). Suitable amino donor can be selected, for example, but not limited to, from the group consisting of ammonium carbamate, ammonia, ammonium salts and mixtures thereof. Preferably it can be selected from the group consisting of ammonia, ammonium carbamate, ammonium carbonate, ammonium chloride, ammonium bromide, ammonium formate, ammonium acetate, ammonium sulfate, ammonium phosphate, and mixtures thereof. In particular, the amino donor is ammonium carbamate or ammonia. More particularly, the amino donor is an ammonia solution kept at a pH at which the enzyme is active and stable and/or which is suitable for the enzymatic reaction. In certain embodiments, the pH value is in the range from about 8.0 to about 1 1.0. Preferably, the pH is from about 9.0 to about 10.0. The pH is preferably adjusted by addition of carbon dioxide (CO2). The amino donor is present in the reaction mixture in a concentration suitable to perform the reaction for example in an amount of about 1 Molar to about 20 Molar. In particular, the amino donor can be present in an amount of 5 Molar to about 15 Molar. Most preferably, the amino donor can be present in an amount of 8 Molar to about 11 Molar.

The solvent can be selected from the group consisting of dimethyl sulfoxide (DMSO), propylene glycol, tocopherol polyethylene glycol succinates (TPGS), glycerol, ethylene glycol, acetonitrile, heptane, isopropanol, dimethylformamide (DMF), toluene, tetrahydrofuran (THF), methyl tert- butyl ether (MTBE), ethyl acetate (EtOAc), acetone, methyl tetrahydrofuran (MeTHF), or mixtures thereof. For example, suitable tocopherol polyethylene glycol succinates (TPGS) can be selected, for example, but not limited to, DL-a-tocopherol polyethylene glycol succinates such as TPGS-750-M, TPGS-1000, TPGS-1500, TPGS-400, TPGS-1100-M, TPGS-2000, TPGS-860- oleate, TPGS-PEG-PPG-PEG-1100, and TPGS-PPG-PEG-70-butyl; and DL-a-tocopherol polypropylene glycol succinates such as TPPG-1000 and TPPG-1000-butyl. Preferably, the solvent is selected from the group consisting of DMSO, propylene glycol, TPGS-750-M, glycerol, ethylene glycol, acetonitrile, heptane, isopropanol, DMF, toluene, THF, MTBE, EtOAc, acetone, MeTHF, or mixtures thereof. More preferably, the solvent is selected from the group consisting of DMSO, propylene glycol, TPGS-750-M, glycerol, ethylene glycol, acetonitrile, heptane, or mixtures thereof.

The enzyme used to perform the reaction outlined in Scheme 2, is an engineered phenylalanine ammonia lyase (PAL). An engineered phenylalanine ammonia lyase comprises, but is not limited to, a polypeptide sequence set forth in the sequences of SEQ ID NOS: 2, 4, 6, 8, 10 or 12. In some additional embodiments, the engineered phenylalanine ammonia lyase comprises a polypeptide sequence exhibits at least one improved property compared to wild-type Anabaena variabilis phenylalanine ammonia lyase. In some additional embodiments, the improved property comprises improved production of compound (C4), or a salt thereof. In some additional embodiments, the improved property comprises improved utilization of compound of formula (C3), or a salt thereof. In yet some additional embodiments, the improved property comprises improved production of compound of formula (C4), or salt thereof from a compound of formula (C3), or a salt thereof.

In yet some additional embodiments, the improved property also comprises an improved production of compound of formula (C5) or a salt thereof, or an improved utilization of the compound of formula (C3), or a salt thereof, and/or an improved production of the compound of formula (C5), or a salt thereof, from the compound of formula (C3) or a salt thereof.

Suitable PALs can be selected from, for example, but not limited to, PAL-124 (nucleotide sequence of SEQ ID NO: 1 , amino-acid sequence of SEQ ID NO: 2), PAL-126 (nucleotide sequence of SEQ ID NO: 3, amino-acid sequence of SEQ ID NO: 4), PAL-128 (nucleotide sequence of SEQ ID NO: 5, amino-acid sequence of SEQ ID NO: 6 ), PAL-129 (nucleotide sequence of SEQ ID NO: 7, amino-acid sequence of SEQ ID NO: 8 ), PAL-130 (nucleotide sequence of SEQ ID NO: 9, amino-acid sequence of SEQ ID NO 10) and PAL-131 (nucleotide sequence of SEQ ID NO: 1 1 , amino-acid sequence of SEQ ID NO 12) or mixtures thereof, from Codexis, Inc., Redwood City, CA, USA. Preferably, the PALs are PAL-128, PAL-129, PAL-130, or PAL-131. Preferably, phenylalanine ammonia lyases are present at a substrate loading concentration of at least about 0.5 g/L, about 0.75 g/L, about 1 g/L, about 1.5 g/L, about 3 g/L, about 5 g/L, about 18 g/L, about 20 g/L, about 25 g/L, about 30 g/L, about 60 g/L, about 80 g/L or more, preferably about 30g/L or more. Such substrate loading achieves a percent conversion of at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 98%, or at least about 99%, or 100%, preferably at least about 80%, in a reaction time of about 42 h or less, or of about 24 h or less, or of about 6 hours or less, or of about 3 hours or less, under suitable reaction conditions. The phenylalanine ammonia lyases are present at an enzyme loading of between about 1 g/L to about 50 g/L, preferably between about 5 g/L to about 32 g/L. The reaction as described in Scheme 2 is advantageously performed when the enzyme is a PAL- 128, when the solvent is DMSO, and the amino donor is ammonium carbamate. In particular, the reaction is performed at a temperature between about 20 °C to about 50 °C, more preferably between about 35 °C to about 45 °C. Performing the reaction under those conditions is particularly advantageous as the addition of the amine group is highly regioselective, thus generating less by-products and improving the yield. The addition of the amine can be achieved with high enantioselectivity. The enantioselectivity is between about 80% to about 100% ee, preferably the enantioselctivity is about 90 to about 100%. In some further embodiments, the improved property comprises improved stability, improved thermostability, improved acid stability, and/or improved alkaline stability.

Compound of formula (C3), or salt thereof, used to perform the reaction as outlined in Scheme 2 above, according to any literature and textbooks available to the skilled person in the art. For example, compound of formula (C3), or salt thereof, can be prepared in two steps, as outlined in Scheme 1 , from compound of formula (C1), so called ortho-vanillin, which is commercially available (e.g. Heo et al Org. Lett. 2013, 15(18), 4718-4721 ; Bugg etal Biochem. 2000, 39, 1522). In another example, compound of formula (C3), or salt thereof, can be prepared in one step, as outlined in Scheme 1 , from compound of formula (C2), so called 2-benzyloxy-3-methoxy benzaldehyde, which is commercially available ( e.g Bugg et al Biochem. 2000, 39, 1522).

Another aspect of the present invention provides a process for preparing a compound of formula (C5), or salt or solvate thereof, by reacting a compound of formula (C4), or salt thereof, with an aldehyde derivative in the presence of an acid, as outlined in Scheme 3 below.

Scheme 3

The acid used to perform the reaction as outlined in Scheme 3, can be any acid that a skilled person would select based on a general textbook. The reaction preferably takes place in the presence of an aqueous inorganic acid, e.g. a hydrohalic acid, such as hydrochloric acid, hydrobromic acid or sulfuric acid, in an appropriate solvent or solvent mixture, e.g. a carboxylic acid, such as acetic acid, and/or water. Preferably, the acid can be selected from, for example, but not limited to, acetic acid (AcOH), hydrochloric acid (HCI), hydrobromic acid (HBr), sulfuric acid (H2SO4), trifluoroacetic acid (TFA), citric acid, formic acid, phosphoric acid, or mixtures thereof, or buffer solutions of those acids. Suitable reaction conditions comprise a buffer solution at a concentration from about 0.2 M to about 0.6 M, preferably from about 0.15 M to 0.5 M, more preferably at least about 0.1 M, e.g, 0.12 M for the process in aqueous phosphoric acid. Most preferably, the acid is acetic acid (AcOH), phosphoric acid, sulfuric acid (H2SO4), or mixtures thereof.

The aldehyde derivative used to perform the reaction as outlined in Scheme 3, can be selected from the group consisting of paraformaldehyde, formaldehyde, 2,4,6-trimethyl-1 ,3,5-trioxane, urotropine and formaline. For example, the aldehyde derivative can be present in an amount between about 1 equivalent to about 5 equivalents. In particular, the aldehyde derivative may be present in an amount of about 1.0 equivalent to about 2 equivalents. Typically, the aldehyde derivative can be present in an amount of about 1.1 equivalents to about 1.5 equivalents.

The reaction as described in Scheme 3 is advantageously performed when the aldehyde derivative is paraformaldehyde, and the acid is AcOH. In particular, the reaction is performed at a temperature between about room temperature to the reflux temperature, e.g. in the range from about 40 °C to about 80 °C, preferably in a range from about 50 °C to about 70 °C, preferably at about 60 °C, more preferably at about 50°C. Performing the reaction under those conditions is particularly advantageous as the reaction can be performed at higher concentration, resulting in higher space-time-yield, shorter reaction time and easier isolation of the product.

2. Enzymatic step

Another aspect of the present disclosure relates to a process for preparing a compound of formula (C5), or a salt thereof, the process comprising the steps of

reacting a compound of formula (C3), or salt thereof, with an engineered phenylalanine ammonia lyase (PAL), an amino donor, in the presence of a solvent; and

adding an acid, and then adding an aldehyde derivative

to obtain a compound of formula (C5), or salt thereof, as outlined in Scheme 4 below,

C3 C5

Scheme 4 Suitable engineered phenylalanine ammonia lyase (PAL), an amino donor, and solvent to transform the above mentioned reaction, are the ones used in Scheme 2 above. Once the conversion of the enzymatic reaction is complete, an acid, optionally in the presence of a solvent, are added to the reaction mixture. Suitable acids are the ones used in Scheme 3 above. Suitable solvents, can be for example, but not limited to, tetrahydrofuran (THF), 2-methyl tetrahydrofuran, diethyl ether, toluene, cyclopentyl methyl ether (CPME), te/f-butylmethyl ether (TBME), xylenes, heptane, methanol, ethanol, 1-butanol, isopropanol, tert-butanol, or mixtures thereof. The preferred solvent of the reaction is one or more solvents selected from toluene, TBME, xylenes, methanol, ethanol, 1 -butanol, isopropanol, tert-butanol, or mixtures thereof. Most preferably, the solvent is toluene, te/f-butyl methyl ether (TBME), or mixtures thereof. The ratio (volume to volume) of said mixture is about 10: 1 , about 1 : 10, about 5: 1 , or about 1 :5, preferably about 1 : 1 of toluene : TBME. The mixture is kept at a pH at which the enzyme precipitates. In certain embodiments, the pH value is in the range from about 0 to about 5.0. Preferably, the pH is from about 1.0 to about 3.0. The pH is preferably adjusted to a pH of about 2.0.

Alternatively, the solvent is toluene, xylenes, methanol, ethanol, 1 -butanol, isopropanol, tert- butanol, or mixtures thereof. The ratio (weight to weight) of said mixture is about 10: 1 , about 1 : 10, about 7:3, about 3:7, about 5: 1 , or about 1 :5, preferably about 7:3 of 1-butanol : xylenes. In one embodiment the solvent is methanol. The mixture is kept at a pH at which the enzyme precipitates. In certain embodiments, the pH value is in the range from about 0 to about 6.0. Preferably, the pH is from about 5.0 to about 6.0. The pH is preferably adjusted to a pH of about 5.5.

Then an aldehyde derivative is added to the reaction mixture. Suitable aldehyde derivative used to perform the reaction are the ones used in Scheme 3 above.

The reaction as described in Scheme 4 is advantageously performed when the enzyme is, e.g., PAL-128 (amino-acid sequence according to SEQ ID NO 6), when the solvent is DMSO, the amino donor is ammonium carbamate, the aldehyde derivative is paraformaldehyde, and the acid is H₂S0₄.

In another embodiment, the reaction as described in Scheme 4 is advantageously performed using alcoholic solvents such as, for example, 1-butanol, methanol, tert-butanol, ethanol, isopropanol alone or in mixtures with other solvents as described herein, e.g., xylenes, the amino donor is ammonium carbamate, the aldehyde derivative is paraformaldehyde, and the acid is H2SO4.

In another embodiment, the reaction as described in Scheme 4 is advantageously performed using alcoholic solvents such as, for example, methanol, 1-butanol, tert-butanol, ethanol, isopropanol alone or in mixtures with other solvents as described herein, e.g., xylenes, the amino donor is ammonium carbamate, the aldehyde derivative is paraformaldehyde, and the acid is H2SO4.

In one embodiment, the reaction is perform as a“one-pot” reaction. In another embodiment, the reaction is conducted in two successive reactions, each reaction product is provided for the next reaction without isolation and purification. In particular, the enzymatic reaction is performed at a temperature between about room temperature to the reflux temperature, e.g. in the range from about 25 °C to about 50 °C, preferably in a range from about 35 °C to about 45 °C, preferably at about 35 °C. Then, after filtration and acidification, the temperature is increased to a range of about 30 °C to about 70 °C, preferably 35 °C to about 65 °C, more preferably at about 40 °C to about 60 °C, when adding the aldehyde derivative. Performing the reaction under those conditions is particularly advantageous as the compound of formula (C5), or salt thereof, can be easily prepared directly from compound of formula (C3), or salt thereof, thus generating less by product and improving the yield. Moreover, using e.g., PAL-130, under the conditions as described herein has the additional advantages that the aqueous layer can be re-used, thus generating less waste, the filtration will be in one single step and thus will be faster and more cost efficient. Moreover, the addition of the amine group is highly regioselective, providing a one to one conversion of the starting material to the desired compound of formula (C5), or a salt thereof. Furthermore, the addition of the amine is achieved in high enantioselectivity. The enantioselectivity is between about 80% to about 100% ee, preferably the enantioselectivity is about 90 to about 100%.

3. Reaction step -> Compound of formula (I)

Another aspect of the present disclosure relates to a process for preparing a compound of formula (I), or a salt, or a solvate thereof, as outlined in Scheme 5 below, the process comprising the steps of reacting a compound of formula (C5), or salt thereof, with a compound of formula (C6), in the presence of a base, to provide a compound of formula (I), or a salt, or a solvate thereof, wherein LG is a leaving group.

cs compound of formula (I)

Scheme 5

Compound of formula (C6) can be any compound with a suitable leaving group (LG), commercially available to the skilled person in the art. Compound of formula (C6) can also be prepared, from commercially available starting materials, according to any literature and textbooks available to the skilled person in the art. The leaving group (LG) can be any suitable leaving group that a skilled person would select to perform the transformation. The leaving group can be selected from, for example, but not limited to, halogen (e.g. chlorine, bromine or iodine), hydroxy group activated through esterification, for example with an imidazole or with an alkanesulfonate group (e.g. methanesulfonyloxy, toluenesulfonyloxy, fluorosulfonyloxy, trifluoromethanesulfonyloxy or nonabutanesulfonyloxy). Preferably, the leaving group is selected from halogen (e.g. chlorine, bromine or iodine), hydroxy group activated through esterification, for example with an imidazole. Most preferably, the leaving group is an imidazole.

The base can be any base that a skilled person would select based on a general textbook. The base can be, for example, sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate, potassium bicarbonate, sodium acetate, potassium acetate, trisodium phosphate, potassium phosphate, lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, barium hydroxide, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, triethylamine, A/,/\/-diisopropylethylamine (DIPEA), sodium te/fbutoxide, potassium te/fbutoxide, 1 ,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1 ,4- diazabicyclo[2.2.2]octane (DABCO), potassium fluoride or cesium fluoride.

For example, compound of formula (I), or salt, or solvate thereof, can be prepared, as outlined in Scheme 5, from compound of formula (C5) or salt thereof, prepared as disclosed herein, following e.g. US 5,246,943; Larhed et al Tetrahedron 2015, 17, 6881-6887.

Another aspect of the present disclosure relates to a process for preparing a pharmaceutical composition, the process comprising the process steps, as disclosed herein, and mixing the obtained compound of formula (I), or a salt, or a solvate thereof, with a pharmaceutically acceptable excipient.

Another aspect of the present disclosure relates to a process for preparing a compound of formula (I), or a salt, or a solvate thereof, the process comprising the steps of:

i. reacting a compound of formula (C3), or a salt thereof, to prepare a compound of formula (C4), or a salt thereof, according to paragraph 1 ,

ii. further reacting the compound of formula (C4), or a salt thereof, to obtain a compound of formula (I), or a salt, or a solvate thereof, as disclosed herein.

i. reacting a compound of formula (C3), or a salt thereof, to prepare a compound of formula (C5), or a salt thereof, according to paragraph 2,

ii. further reacting the compound of formula (C5), or a salt thereof, to obtain a compound of formula (I), or a salt, or a solvate thereof, as disclosed herein.

4. Enzymes:

Commercially available PALs showed poor or no activity on substrates containing bulky or electron rich substituent(s) on the aromatic ring, and poor stability under industrially useful process conditions (e.g., in the presence of organic solvents or elevated temperature). Thus, engineered PALs with improved PALs properties were designed to specifically prepare the intermediates for the synthesis of a compound of formula (I) or a salt, or a solvate thereof.

In one aspect, the present disclosure relates to a process for preparing compound of formula (I), or a salt, or a solvate thereof, using an enzymatic reaction wherein the enzymatic reaction is performed in the presence of a engineered phenylalanine ammonia lyase as disclosed herein.

In some embodiments, the engineered phenylalanine ammonia lyase comprises, but is not limited to, a polypeptide sequence set forth in the sequences of SEQ ID NOS: 2, 4, 6, 8, 10 or 12. Further variants having undergone evolution and retaining the improved property can be used in the present process. In further embodiments, the engineered phenylalanine ammonia lyase comprises a polypeptide sequence and exhibits at least one improved property compared to wild- type Anabaena variabilis phenylalanine ammonia lyase. In some additional embodiments, the improved property comprises improved production of compound of formula (C4), or a salt thereof.

In some additional embodiments, the improved property comprises improved utilization of the compound of formula (C3), or a salt thereof. In yet some additional embodiments, the improved property comprises improved production of the compound of formula (C4), or a salt thereof, from the compound of formula (C3), or a salt thereof.

In yet some additional embodiments, the improved property comprises improved enantioselectivity. In some further embodiments, the improved property comprises improved stability. In some additional embodiments, the improved property comprises improved thermostability, improved acid stability, and/or improved alkaline stability. In some further embodiments, the engineered phenylalanine ammonia lyase is purified. In present invention also provides compositions comprising at least one engineered phenylalanine ammonia lyase provided herein. In present invention also provides compositions comprising an engineered phenylalanine ammonia lyase provided herein.

Suitable engineered phenylalanine ammonia lyase enzymes used to prepare a compound of formula (I), or a salt, or a solvate thereof, as disclosed herein, comprise, for example, but are not limited to, polypeptide sequences having at least 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or more sequence identity to SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12 or a functional fragment thereof.

In another aspect of the present invention, the enzymatic reaction takes place in the presence of an engineered, (S)-selective, phenylalanine ammonia lyase selected from, for example, but not limited to, PAL-124 (nucleotide sequence of SEQ ID NO: 1 , amino-acid sequence of SEQ ID NO: 2), PAL-126 (nucleotide sequence of SEQ ID NO: 3, amino-acid sequence of SEQ ID NO: 4), PAL-128 (nucleotide sequence of SEQ ID NO: 5, amino-acid sequence of SEQ ID NO: 6 ), PAL- 129 (nucleotide sequence of SEQ ID NO: 7, amino-acid sequence of SEQ ID NO: 8 ), PAL-130 (nucleotide sequence of SEQ ID NO: 9, amino-acid sequence of SEQ ID NO 10) and PAL-131 (nucleotide sequence of SEQ ID NO: 1 1 , amino-acid sequence of SEQ ID NO 12) from Codexis, Inc., Redwood City, CA, USA, with an amine donor, in the presence of a suitable solvent, at pH and temperature conditions, as disclosed herein above.

In some examples, engineered PALs or evolutions thereof can be produced as follows:

A synthetic gene encoding any Anabaena variabilis phenylalanine ammonia lyase variant as described above which has activity to produce compound of formula (C4), or a salt thereof, starting from a compound of formula (C3), or a salt thereof, is chosen as the parent gene optimized for expression in E. coli is cloned into a pCK110900 vector. W3110 E. coli cells are transformed with the respective plasmid containing the parent PAL encoding gene and plated on LB agar plates containing 1 % glucose and 30 pg/ml chloramphenicol (CAM), and grown overnight at 37°C. Monoclonal colonies are picked and inoculated into 180 pi LB containing 1 % glucose and 30 pg/mL chloramphenicol and placed in the wells of 96-well shallow-well microtiter plates. The plates are sealed with 02-permeable seals and cultures are grown overnight at 30°C, 200 rpm and 85% humidity. Then, 10 mI of each of the cell cultures are transferred into the wells of 96-well deep-well plates containing 390 mI TB and 30 pg/mL CAM. The deep-well plates are sealed with 02-permeable seals and incubated at 30°C, 250 rpm and 85% humidity until OD600 0.6-0.8 is reached. The cell cultures are then induced by adding isopropyl thioglycoside (IPTG) to a final concentration of 1 mM and incubated overnight at 30°C with 250 rpm shaking. The cells are then pelleted using centrifugation at 4,000 rpm for 10 min. The supernatants are discarded and the pellets frozen at -80°C prior to lysis.

Preparation of high throughput PAL-containinq cell lysates:

Frozen pellets prepared as described above are lysed with 400 mI lysis buffer containing 100 mM triethanolamine buffer, pH 7.5, 1 g/L lysozyme and 0.5 g/L. The lysis mixture is shaken at room temperature for 2 hours. The plate is then centrifuged for 15 min at 4000 rpm and 4°C. The supernatants are then used in biocatalytic reactions as clarified lysate to determine enzymatic activity.

Preparation of Ivophilized lysates from shake flask (SF) cultures:

A single colony containing the desired gene picked from an LB agar plates with 1 % glucose and 30 pg/ml CAM, and incubated overnight at 37°C is transferred to 6 ml of LB with 1 % glucose and 30 pg/ml CAM. The culture is grown for 18 h at 30°C, 250 rpm, and subcultured approximately 1 :50 into 250 ml of TB containing 30 pg/ml CAM, to a final OD600 of about 0.05. The subculture was grown for approximately 195 minutes at 30°C, 250 rpm, to an OD600 between 0.6-0.8, and induced with 1 mM IPTG. The subculture is then grown for 20 h at 30°C and 250 rpm. The subculture is centrifuged at 4000 rpm for 20 min. The supernatant is discarded, and the pellet is resuspended in 35 ml of 25 mM triethanolamine buffer, pH 7.5. The cells are lysed using a Microfluidizer® processor system (Microfluidics) at 18,000 psi. The lysate is pelleted (10,000 rpm x 60 min), and the supernatant is frozen and lyophilized to generate shake flake (SF) enzyme powder.

Improved PAL variants for production of compound of formula (C4), or a salt thereof, or compound of formula (C5), or a salt thereof:

A variant of wild type PAL from Anabaena variabilis is chosen as the initial parent enzyme. Libraries of engineered genes are produced using well-established techniques (e.g., saturation mutagenesis, and recombination of previously identified beneficial mutations). The polypeptides encoded by each gene are produced in high throughput as described above, and the clarified lysates are generated as described above. Each 100 pL reaction was carried out in 96-well shallow well microtiter plates with 50 % (v/v) clarified cell lysate, 10 mM compound (1), 1 M ammonium carbonate, pH ~ 9. The plates were heat sealed and incubated at 30°C and agitated at 500 RPM in an Infors Thermotron® shaker overnight. The plate was removed and quenched by adding 1 volume (100 pl_) of methanol to each well followed by mixing and centrifugation. The supernatant was then diluted an additional amount in methanol as needed to be above the limit of detection and within the linear range of the analysis. The analysis was performed on the Agilent RapidFire 365 high throughput mass spectrometer using the manufacturer’s protocols. Activity relative to the resulting PAL variant is calculated as the area under the curve of the product formed by the variant, as compared to that of the starting variant, as determined by the previously described RapidFire analysis.

The quantities of reactants used in the amination reaction will generally vary depending on the quantities of product desired, and concomitantly the amount of phenylalanine ammonia lyase substrate employed. Those having ordinary skill in the art will readily understand how to vary these quantities to tailor them to the desired level of productivity and scale of production. In some embodiments, the order of addition of reactants is not critical. The reactants may be added together at the same time to a solvent (e.g., monophasic solvent, biphasic aqueous co-solvent system, and the like), or alternatively, some of the reactants may be added separately, and some together at different time points. For example, the phenylalanine ammonia lyase, and phenylalanine ammonia lyase substrate may be added first to a solvent as disclosed herein, e.g., DMSO.

In some examples, an isolated polynucleotide encoding any of the engineered enzyme polypeptides herein is manipulated in a variety of ways to facilitate expression of the enzyme polypeptide. In some examples, the polynucleotides encoding the enzyme polypeptides comprise expression vectors where one or more control sequences is present to regulate the expression of the enzyme polynucleotides and/or polypeptides. Manipulation of the isolated polynucleotide prior to its insertion into a vector may be desirable or necessary depending on the expression vector utilized. Techniques for modifying polynucleotides and nucleic acid sequences utilizing recombinant DNA methods are well known in the art. In some examples, the control sequences include among others, promoters, leader sequences, polyadenylation sequences, propeptide sequences, signal peptide sequences, and transcription terminators. In some examples, suitable promoters are selected based on the host cells selection. For bacterial host cells, suitable promoters for directing transcription of the nucleic acid constructs of the present disclosure, include, but are not limited to promoters obtained from the E. coli lac operon, Streptomyces coelicolor agarase gene (dagA), Bacillus subtilis levansucrase gene (sacB), Bacillus licheniformis alpha-amylase gene (amyL), Bacillus stearothermophilus maltogenic amylase gene (amyM), Bacillus amyloliquefaciens alpha-amylase gene (amyQ), Bacillus licheniformis penicillinase gene (penP), Bacillus subtilis xylA and xylB genes, and prokaryotic beta-lactamase gene (e.g., Villa- Kamaroff et at, Proc. Natl Acad. Sci. USA 75: 3727-3731 [1978]), as well as the tac promoter (e.g., DeBoer et at, Proc. Natl Acad. Sci. USA 80: 21-25 [1983]). Exemplary promoters for filamentous fungal host cells, include, but are not limited to promoters obtained from the genes for Aspergillus oryzae TAKA amylase, Rhizomucor miehei aspartic proteinase, Aspergillus niger neutral alpha-amylase, Aspergillus niger acid stable alpha-amylase, Aspergillus niger or Aspergillus awamori glucoamylase (glaA), Rhizomucor miehei lipase, Aspergillus oryzae alkaline protease, Aspergillus oryzae those phosphate isomerase, Aspergillus nidulans acetamidase, and Fusarium oxysporum trypsin-like protease (e.g., WO 96/00787), as well as the NA2-tpi promoter (a hybrid of the promoters from the genes for Aspergillus niger neutral alpha-amylase and Aspergillus oryzae those phosphate isomerase), and mutant, truncated, and hybrid promoters thereof. Exemplary yeast cell promoters can be from the genes can be from the genes for Saccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiae galactokinase (GAL1), Saccharomyces cerevisiae alcohol dehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP), and Saccharomyces cerevisiae 3-phosphoglycerate kinase. Other useful promoters for yeast host cells are known in the art (e.g., Romanos et al. , Yeast 8:423-488 [1992]).

In some examples, the control sequence is also a suitable transcription terminator sequence (i.e. , a sequence recognized by a host cell to terminate transcription). In some examples, the terminator sequence is operably linked to the 3' terminus of the nucleic acid sequence encoding the enzyme polypeptide. Any suitable terminator which is functional in the host cell of choice finds use herein. Exemplary transcription terminators for filamentous fungal host cells can be obtained from the genes for Aspergillus oryzae TAKA amylase, Aspergillus niger glucoamylase, Aspergillus nidulans anthranilate synthase, Aspergillus niger alpha-glucosidase, and Fusarium oxysporum trypsin-like protease. Exemplary terminators for yeast host cells can be obtained from the genes for Saccharomyces cerevisiae enolase, Saccharomyces cerevisiae cytochrome C (CYC1), and Saccharomyces cerevisiae glyceraldehyde-3-phosphate dehydrogenase. Other useful terminators for yeast host cells are known in the art (e.g., Romanos et al., supra).

In some examples, the control sequence is also a suitable leader sequence (i.e., a non-translated region of an mRNA that is important for translation by the host cell). In some examples, the leader sequence is operably linked to the 5' terminus of the nucleic acid sequence encoding the enzyme polypeptide. Any suitable leader sequence that is functional in the host cell of choice find use herein. Exemplary leaders for filamentous fungal host cells are obtained from the genes for Aspergillus oryzae TAKA amylase, and Aspergillus nidulans those phosphate isomerase. Suitable leaders for yeast host cells are obtained from the genes for Saccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiae 3-phosphoglycerate kinase, Saccharomyces cerevisiae alpha-factor, and Saccharomyces cerevisiae alcohol dehydrogenase/glyceraldehyde- 3-phosphate dehydrogenase (ADH2/GAP).

In some examples, the control sequence is also a polyadenylation sequence (i.e. , a sequence operably linked to the 3' terminus of the nucleic acid sequence and which, when transcribed, is recognized by the host cell as a signal to add polyadenosine residues to transcribed mRNA). Any suitable polyadenylation sequence which is functional in the host cell of choice finds use herein. Exemplary polyadenylation sequences for filamentous fungal host cells include, but are not limited to the genes for Aspergillus oryzae TAKA amylase, Aspergillus niger glucoamylase, Aspergillus nidulans anthranilate synthase, Fusarium oxysporum trypsin-like protease, and Aspergillus niger alpha-glucosidase. Useful polyadenylation sequences for yeast host cells are known (e.g., Guo and Sherman, Mol. Cell. Bio., 15:5983-5990 [1995]).

In some examples, the control sequence comprises a signal peptide (i.e., a coding region that codes for an amino acid sequence linked to the amino terminus of a polypeptide and directs the encoded polypeptide into the cell's secretory pathway). In some examples, the 5' end of the coding sequence of the nucleic acid sequence inherently contains a signal peptide coding region naturally linked in translation reading frame with the segment of the coding region that encodes the secreted polypeptide. Alternatively, in some examples, the 5' end of the coding sequence contains a signal peptide coding region that is foreign to the coding sequence. Any suitable signal peptide coding region which directs the expressed polypeptide into the secretory pathway of a host cell of choice finds use for expression of the engineered polypeptide(s). Effective signal peptide coding regions for bacterial host cells are the signal peptide coding regions include, but are not limited to those obtained from the genes for Bacillus NCIB 1 1837 maltogenic amylase, Bacillus stearothermophilus alpha-amylase, Bacillus licheniformis subtilisin, Bacillus licheniformis beta-lactamase, Bacillus stearothermophilus neutral proteases (nprT, nprS, nprM), and Bacillus subtilis prsA. Further signal peptides are known in the art (See e.g., Simonen and Palva, Microbiol. Rev., 57: 109-137 [1993]). In some examples, effective signal peptide coding regions for filamentous fungal host cells include, but are not limited to the signal peptide coding regions obtained from the genes for Aspergillus oryzae TAKA amylase, Aspergillus niger neutral amylase, Aspergillus niger glucoamylase, Rhizomucor miehei aspartic proteinase, Humicola insolens cellulase, and Humicola lanuginosa lipase. Useful signal peptides for yeast host cells include, but are not limited to those from the genes for Saccharomyces cerevisiae alpha-factor and Saccharomyces cerevisiae invertase.

In some examples, the control sequence is also a propeptide coding region that codes for an amino acid sequence positioned at the amino terminus of a polypeptide. The resultant polypeptide is referred to as a“proenzyme,”“propolypeptide,” or“zymogen.” A propolypeptide can be converted to a mature active polypeptide by catalytic or autocatalytic cleavage of the propeptide from the propolypeptide. The propeptide coding region may be obtained from any suitable source, including, but not limited to the genes for Bacillus subtilis alkaline protease (aprE), Bacillus subtilis neutral protease (nprT), Saccharomyces cerevisiae alpha-factor, Rhizomucor miehei aspartic proteinase, and Myceliophthora thermophila lactase (e.g., WO 95/33836). Where both signal peptide and propeptide regions are present at the amino terminus of a polypeptide, the propeptide region is positioned next to the amino terminus of a polypeptide and the signal peptide region is positioned next to the amino terminus of the propeptide region.

In some examples, regulatory sequences are also utilized. These sequences facilitate the regulation of the expression of the polypeptide relative to the growth of the host cell. Examples of regulatory systems are those that cause the expression of the gene to be turned on or off in response to a chemical or physical stimulus, including the presence of a regulatory compound. In prokaryotic host cells, suitable regulatory sequences include, but are not limited to the lac, tac, and trp operator systems. In yeast host cells, suitable regulatory systems include, but are not limited to the ADH2 system or GAL1 system. In filamentous fungi, suitable regulatory sequences include, but are not limited to the TAKA alpha-amylase promoter, Aspergillus niger glucoamylase promoter, and Aspergillus oryzae glucoamylase promoter.

In another example, a recombinant expression vector comprises a polynucleotide encoding an engineered enzyme polypeptide, and one or more expression regulating regions such as a promoter and a terminator, a replication origin, etc., depending on the type of hosts into which they are to be introduced. In some examples, the various nucleic acid and control sequences described herein are joined together to produce recombinant expression vectors which include one or more convenient restriction sites to allow for insertion or substitution of the nucleic acid sequence encoding the enzyme polypeptide at such sites. Alternatively, in some examples, the nucleic acid sequence as described herein is expressed by inserting the nucleic acid sequence or a nucleic acid construct comprising the sequence into an appropriate vector for expression. In some examples involving the creation of the expression vector, the coding sequence is located in the vector so that the coding sequence is operably linked with the appropriate control sequences for expression.

The recombinant expression vector may be any suitable vector (e.g., a plasmid or virus), that can be conveniently subjected to recombinant DNA procedures and bring about the expression of the enzyme polynucleotide sequence. The choice of the vector typically depends on the compatibility of the vector with the host cell into which the vector is to be introduced. The vectors may be linear or closed circular plasmids. In some examples, the expression vector is an autonomously replicating vector (i.e. , a vector that exists as an extra-chromosomal entity, the replication of which is independent of chromosomal replication, such as a plasmid, an extra-chromosomal element, a minichromosome, or an artificial chromosome). The vector may contain any means for assuring self-replication. In some alternative examples, the vector is one in which, when introduced into the host cell, it is integrated into the genome and replicated together with the chromosome(s) into which it has been integrated. Furthermore, in some examples, a single vector or plasmid, or two or more vectors or plasmids which together contain the total DNA to be introduced into the genome of the host cell, and/or a transposon is utilized.

In some examples, the expression vector contains one or more selectable markers, which permit easy selection of transformed cells. A“selectable marker” is a gene, the product of which provides for biocide or viral resistance, resistance to heavy metals, prototrophy to auxotrophs, and the like. Examples of bacterial selectable markers include, but are not limited to the dal genes from Bacillus subtilis or Bacillus licheniformis, or markers, which confer antibiotic resistance such as ampicillin, kanamycin, chloramphenicol or tetracycline resistance. Suitable markers for yeast host cells include, but are not limited to ADE2, HIS3, LEU2, LYS2, MET3, TRP1 , and URA3. Selectable markers for use in filamentous fungal host cells include, but are not limited to, amdS (acetamidase; e.g., from A. nidulans or A. orzyae), argB (ornithine carbamoyltransferases), bar (phosphinothricin acetyltransferase; e.g., from S. hygroscopicus), hph (hygromycin phosphotransferase), niaD (nitrate reductase), pyrG (orotidine-5'-phosphate decarboxylase; e.g., from A. nidulans or A. orzyae), sC (sulfate adenyltransferase), and trpC (anthranilate synthase), as well as equivalents thereof.

In another example a host cell comprises at least one polynucleotide encoding at least one engineered enzyme polypeptide as described herein, the polynucleotide(s) being operatively linked to one or more control sequences for expression of the engineered enzyme enzyme(s) in the host cell. Host cells suitable for use in expressing the polypeptides encoded by the expression vectors as described herein are well known in the art and include but are not limited to, bacterial cells, such as E. coli, Vibrio fluvialis, Streptomyces and Salmonella typhimurium cells; fungal cells, such as yeast cells (e.g., Saccharomyces cerevisiae or Pichia pastoris (ATCC Accession No. 201 178)); insect cells such as Drosophila S2 and Spodoptera Sf9 cells; animal cells such as CHO, COS, BHK, 293, and Bowes melanoma cells; and plant cells. Exemplary host cells also include various Escherichia coli strains (e.g., W3110 (AfhuA) and BL21). Examples of bacterial selectable markers include, but are not limited to the dal genes from Bacillus subtilis or Bacillus licheniformis, or markers, which confer antibiotic resistance such as ampicillin, kanamycin, chloramphenicol, and or tetracycline resistance. In some examples, the expression vectors contain an element(s) that permits integration of the vector into the host cell's genome or autonomous replication of the vector in the cell independent of the genome. In some examples involving integration into the host cell genome, the vectors rely on the nucleic acid sequence encoding the polypeptide or any other element of the vector for integration of the vector into the genome by homologous or non-homologous recombination.

In some alternative examples, the expression vectors contain additional nucleic acid sequences for directing integration by homologous recombination into the genome of the host cell. The additional nucleic acid sequences enable the vector to be integrated into the host cell genome at a precise location(s) in the chromosome(s). To increase the likelihood of integration at a precise location, the integrational elements preferably contain a sufficient number of nucleotides, such as 100 to 10,000 base pairs, preferably 400 to 10,000 base pairs, and most preferably 800 to 10,000 base pairs, which are highly homologous with the corresponding target sequence to enhance the probability of homologous recombination. The integrational elements may be any sequence that is homologous with the target sequence in the genome of the host cell. Furthermore, the integrational elements may be non-encoding or encoding nucleic acid sequences. On the other hand, the vector may be integrated into the genome of the host cell by non-homologous recombination.

For autonomous replication, the vector may further comprise an origin of replication enabling the vector to replicate autonomously in the host cell in question. Examples of bacterial origins of replication are P15A ori or the origins of replication of plasmids pBR322, pUC19, pACYCI77 (which plasmid has the P15A ori), or pACYC184 permitting replication in E. coli, and pUB110, pE194, or pTA1060 permitting replication in Bacillus. Examples of origins of replication for use in a yeast host cell are the 2 micron origin of replication, ARS1 , ARS4, the combination of ARS1 and CEN3, and the combination of ARS4 and CEN6. The origin of replication may be one having a mutation which makes it’s functioning temperature-sensitive in the host cell (e.g., Ehrlich, Proc. Natl. Acad. Sci. USA 75:1433 [1978]).

In some examples, more than one copy of a nucleic acid sequence as described herein is inserted into the host cell to increase production of the gene product. An increase in the copy number of the nucleic acid sequence can be obtained by integrating at least one additional copy of the sequence into the host cell genome or by including an amplifiable selectable marker gene with the nucleic acid sequence where cells containing amplified copies of the selectable marker gene, and thereby additional copies of the nucleic acid sequence, can be selected for by cultivating the cells in the presence of the appropriate selectable agent.

Many of the expression vectors for use herein are commercially available. Suitable commercial expression vectors include, but are not limited to the p3xFLAGTMTM expression vectors (Sigma- Aldrich Chemicals), which include a CMV promoter and hGH polyadenylation site for expression in mammalian host cells and a pBR322 origin of replication and ampicillin resistance markers for amplification in E. coli. Other suitable expression vectors include, but are not limited to pBluescriptll SK(-) and pBK-CMV (Stratagene), and plasmids derived from pBR322 (Gibco BRL), pUC (Gibco BRL), pREP4, pCEP4 (Invitrogen) or pPoly ( e.g., Lathe et at., Gene 57: 193-201 [1987]).

Thus, in some examples, a vector comprising a sequence encoding at least one variant phenylalanine ammonia lyase is transformed into a host cell in order to allow propagation of the vector and expression of the variant phenylalanine ammonia lyase(s). In some examples, the variant phenylalanine ammonia lyases are post-translationally modified to remove the signal peptide and in some cases may be cleaved after secretion. In some examples, the transformed host cell described above is cultured in a suitable nutrient medium under conditions permitting the expression of the variant phenylalanine ammonia lyase(s). Any suitable medium useful for culturing the host cells finds use herein, including, but not limited to minimal or complex media containing appropriate supplements. In some examples, host cells are grown in high throughput media. Suitable media are available from various commercial suppliers or may be prepared according to published recipes (e.g., in catalogues of the American Type Culture Collection).

In another example, host cells comprise a polynucleotide encoding a variant phenylalanine ammonia lyase polypeptide provided herein, the polynucleotide being operatively linked to one or more control sequences for expression of the phenylalanine ammonia lyase enzyme in the host cell. Host cells for use in expressing the phenylalanine ammonia lyase polypeptides encoded by the expression vectors described herein are well known in the art and include but are not limited to, bacterial cells, such as E. coli, Bacillus megaterium, Lactobacillus kefir, Streptomyces and Salmonella typhimurium cells; fungal cells, such as yeast cells (e.g., Saccharomyces cerevisiae or Pichia pastoris (ATCC Accession No. 201178)); insect cells such as Drosophila S2 and Spodoptera Sf9 cells; animal cells such as CHO, COS, BHK, 293, and Bowes melanoma cells; and plant cells. Appropriate culture media and growth conditions for the above-described host cells are well known in the art.

Polynucleotides for expression of the phenylalanine ammonia lyase may be introduced into cells by various methods known in the art. Techniques include among others, electroporation, biolistic particle bombardment, liposome mediated transfection, calcium chloride transfection, and protoplast fusion. Various methods for introducing polynucleotides into cells are known to those skilled in the art. In some examples, the host cell is a eukaryotic cell. Suitable eukaryotic host cells include, but are not limited to, fungal cells, algal cells, insect cells, and plant cells. Suitable fungal host cells include, but are not limited to, Ascomycota, Basidiomycota, Deuteromycota, Zygomycota, Fungi imperfecti. In some examples, the fungal host cells are yeast cells and filamentous fungal cells. The filamentous fungal host cells include all filamentous forms of the subdivision Eumycotina and Oomycota. Filamentous fungi are characterized by a vegetative mycelium with a cell wall composed of chitin, cellulose and other complex polysaccharides. The filamentous fungal host cells are morphologically distinct from yeast.

In some examples, the filamentous fungal host cells are of any suitable genus and species, including, but not limited to Achlya, Acremonium, Aspergillus, Aureobasidium, Bjerkandera, Ceriporiopsis, Cephalosporium, Chrysosporium, Cochliobolus, Corynascus, Cryphonectria, Cryptococcus, Coprinus, Coriolus, Diplodia, Endothis, Fusarium, Gibberella, Gliocladium, Humicola, Hypocrea, Myceliophthora, Mucor, Neurospora, Penicillium, Podospora, Phlebia, Piromyces, Pyricularia, Rhizomucor, Rhizopus, Schizophyllum, Scytalidium, Sporotrichum, Talaromyces, Thermoascus, Thielavia, Trametes, Tolypocladium, Trichoderma, Verticillium, and/or Volvariella, and/or teleomorphs, or anamorphs, and synonyms, basionyms, or taxonomic equivalents thereof.

In some examples, the host cell is a yeast cell, including but not limited to cells of Candida, Hansenula, Saccharomyces, Schizosaccharomyces, Pichia, Kluyveromyces, or Yarrowia species. In some examples, the yeast cell is Hansenula polymorpha, Saccharomyces cerevisiae, Saccharomyces carlsbergensis, Saccharomyces diastaticus, Saccharomyces norbensis, Saccharomyces kluyveri, Schizosaccharomyces pombe, Pichia pastoris, Pichia finlandica, Pichia trehalophila, Pichia kodamae, Pichia membranaefaciens, Pichia opuntiae, Pichia thermotolerans, Pichia salictaria, Pichia quercuum, Pichia pijperi, Pichia stipitis, Pichia methanolica, Pichia angusta, Kluyveromyces lactis, Candida albicans, or Yarrowia lipolytica.

In some examples, the host cell is an algal cell such as Chlamydomonas (e.g., C. reinhardtii) and Phormidium (P. sp. ATCC29409).

In some other examples, the host cell is a prokaryotic cell. Suitable prokaryotic cells include, but are not limited to Gram-positive, Gram-negative and Gram-variable bacterial cells. Any suitable bacterial organism finds use herein, including but not limited to Agrobacterium, Alicyclobacillus, Anabaena, Anacystis, Acinetobacter, Acidothermus, Arthrobacter, Azobacter, Bacillus, Bifidobacterium, Brevibacterium, Butyrivibrio, Buchnera, Campestris, Camplyobacter, Clostridium, Corynebacterium, Chromatium, Coprococcus, Escherichia, Enterococcus, Enterobacter, Erwinia, Fusobacterium, Faecalibacterium, Francisella, Flavobacterium, Geobacillus, Haemophilus, Helicobacter, Klebsiella, Lactobacillus, Lactococcus, llyobacter, Micrococcus, Microbacterium, Mesorhizobium, Methylobacterium, Methylobacterium, Mycobacterium, Neisseria, Pantoea, Pseudomonas, Prochlorococcus, Rhodobacter, Rhodopseudomonas, Rhodopseudomonas, Roseburia, Rhodospirillum, Rhodococcus, Scenedesmus, Streptomyces, Streptococcus, Synecoccus, Saccharomonospora, Staphylococcus, Serratia, Salmonella, Shigella, Thermoanaerobacterium, Tropheryma, Tularensis, Temecula, Thermosynechococcus, Thermococcus, Ureaplasma, Xanthomonas, Xylella, Yersinia and Zymomonas. In some examples, the host cell is a species of Agrobacterium, Acinetobacter, Azobacter, Bacillus, Bifidobacterium, Buchnera, Geobacillus, Campylobacter, Clostridium, Corynebacterium, Escherichia, Enterococcus, Erwinia, Flavobacterium, Lactobacillus, Lactococcus, Pantoea, Pseudomonas, Staphylococcus, Salmonella, Streptococcus, Streptomyces, or Zymomonas. In some examples, the bacterial host strain is non-pathogenic to humans. In some examples the bacterial host strain is an industrial strain. Numerous bacterial industrial strains are known and suitable herein. In some examples, the bacterial host cell is an Agrobacterium species (e.g., A. radiobacter, A. rhizogenes, and A. rubi). In some examples, the bacterial host cell is an Arthrobacter species (e.g., A. aurescens, A. citreus, A. globiformis, A. hydrocarboglutamicus, A. mysorens, A. nicotianae, A. paraffineus, A. protophonniae, A. roseoparqffinus, A. sulfureus, and A. ureafaciens). In some examples, the bacterial host cell is a Bacillus species (e.g., B. thuringensis, B. anthracis, B. megaterium, B. subtilis, B. lentus, B. circulans, B. pumilus, B. lautus, B.coagulans, B. brevis, B. firmus, B. alkaophius, B. licheniformis, B. clausii, B. stearothermophilus, B. halodurans, and B. amyloliquefaciens). In some examples, the host cell is an industrial Bacillus strain including but not limited to B. subtilis, B. pumilus, B. licheniformis, B. megaterium, B. clausii, B. stearothermophilus, or B. amyloliquefaciens. In some examples, the Bacillus host cells are B. subtilis, B. licheniformis, B. megaterium, B. stearothermophilus, and/or B. amyloliquefaciens. In some examples, the bacterial host cell is a Clostridium species (e.g., C. acetobutylicum, C. tetani E88, C. lituseburense, C. saccharobutylicum, C. perfringens, and C. beijerinckii). In some examples, the bacterial host cell is a Corynebacterium species (e.g., C. glutamicum and C. acetoacidophilum). In some examples the bacterial host cell is an Escherichia species (e.g., E. coli). In some examples, the host cell is Escherichia coli W31 10. In some examples, the bacterial host cell is an Erwinia species (e.g., E. uredovora, E. carotovora, E. ananas, E. herbicola, E. punctata, and E. terreus). In some examples, the bacterial host cell is a Pantoea species (e.g., P. citrea, and P. agglomerans). In some examples the bacterial host cell is a Pseudomonas species (e.g., P. putida, P. aeruginosa, P. mevalonii, and P. sp. D-0I 10). In some examples, the bacterial host cell is a Streptococcus species (e.g., S. equisimiles, S. pyogenes, and S. uberis). In some examples, the bacterial host cell is a Streptomyces species (e.g., S. ambofaciens, S. achromogenes, S. avermitilis, S. coelicolor, S. aureofaciens, S. aureus, S. fungicidicus, S. griseus, and S. lividans). In some examples, the bacterial host cell is a Zymomonas species (e.g., Z. mobilis, and Z. lipolytica). Many prokaryotic and eukaryotic strains that find use herein are readily available to the public from a number of culture collections such as American Type Culture Collection (ATCC), Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSM), Centraalbureau Voor Schimmelcultures (CBS), and Agricultural Research Service Patent Culture Collection, Northern Regional Research Center (NRRL).

In some examples, host cells are genetically modified to have characteristics that improve protein secretion, protein stability and/or other properties desirable for expression and/or secretion of a protein. Genetic modification can be achieved by genetic engineering techniques and/or classical microbiological techniques (e.g., chemical or UV mutagenesis and subsequent selection). Indeed, in some examples, combinations of recombinant modification and classical selection techniques are used to produce the host cells. Using recombinant technology, nucleic acid molecules can be introduced, deleted, inhibited or modified, in a manner that results in increased yields of phenylalanine ammonia lyase variant(s) within the host cell and/or in the culture medium. For example, knockout of Alp1 function results in a cell that is protease deficient, and knockout of pyr5 function results in a cell with a pyrimidine deficient phenotype. In one genetic engineering approach, homologous recombination is used to induce targeted gene modifications by specifically targeting a gene in vivo to suppress expression of the encoded protein. In alternative approaches, siRNA, antisense and/or ribozyme technology find use in inhibiting gene expression. A variety of methods are known in the art for reducing expression of protein in cells, including, but not limited to deletion of all or part of the gene encoding the protein and site-specific mutagenesis to disrupt expression or activity of the gene product (e.g., Chaveroche et al., Nucl. Acids Res., 28:22 e97 [2000]; Cho et al., Molec. Plant Microbe Interact., 19:7-15 [2006]; Maruyama and Kitamoto, Biotechnol Lett., 30: 1811-1817 [2008]; Takahashi et al., Mol. Gen. Genom., 272: 344-352 [2004]; and You et al., Arch. Micriobiol., 191 :615-622 [2009]). Random mutagenesis, followed by screening for desired mutations also finds use (See e.g., Combier et al., FEMS Microbiol. Lett., 220: 141-8 [2003]; and Firon et al., Eukary. Cell 2:247-55 [2003]).

Introduction of a vector or DNA construct into a host cell can be accomplished using any suitable method known in the art, including but not limited to calcium phosphate transfection, DEAE- dextran mediated transfection, PEG-mediated transformation, electroporation, or other common techniques known in the art. In some examples, the Escherichia coli expression vector pCK100900i (US 9,714,437) finds use.

In some examples, the engineered host cells (i.e.,“recombinant host cells”) as described herein are cultured in conventional nutrient media modified as appropriate for activating promoters, selecting transformants, or amplifying the phenylalanine ammonia lyase polynucleotide. Culture conditions, such as temperature, pH and the like, are those previously used with the host cell selected for expression, and are well-known to those skilled in the art. As noted, many standard references and texts are available for the culture and production of many cells, including cells of bacterial, plant, animal (especially mammalian) and archaebacterial origin.

In some examples, cells expressing the variant phenylalanine ammonia lyase polypeptides are grown under batch or continuous fermentations conditions. Classical“batch fermentation” is a closed system, wherein the compositions of the medium is set at the beginning of the fermentation and is not subject to artificial alternations during the fermentation. A variation of the batch system is a“fed-batch fermentation” which also finds use herein. In this variation, the substrate is added in increments as the fermentation progresses. Fed-batch systems are useful when catabolite repression is likely to inhibit the metabolism of the cells and where it is desirable to have limited amounts of substrate in the medium. Batch and fed-batch fermentations are common and well known in the art.“Continuous fermentation” is an open system where a defined fermentation medium is added continuously to a bioreactor and an equal amount of conditioned medium is removed simultaneously for processing. Continuous fermentation generally maintains the cultures at a constant high density where cells are primarily in log phase growth. Continuous fermentation systems strive to maintain steady state growth conditions. Methods for modulating nutrients and growth factors for continuous fermentation processes as well as techniques for maximizing the rate of product formation are well known in the art of industrial microbiology.

In some examples, cell-free transcription/translation systems find use in producing variant phenylalanine ammonia lyase(s). Several systems are commercially available and the methods are well-known to those skilled in the art.

Methods of making variant phenylalanine ammonia lyase polypeptides or biologically active fragments thereof are described herein. In some examples, the method comprises: providing a host cell transformed with a polynucleotide encoding an amino acid sequence that comprises at least about 70% (or at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99%) sequence identity to SEQ ID NO: 2, 4, 6, 8, 10, 12 or further variants comprising at least one further mutation as provided herein; culturing the transformed host cell in a culture medium under conditions in which the host cell expresses the encoded variant phenylalanine ammonia lyase polypeptide; and optionally recovering or isolating the expressed variant phenylalanine ammonia lyase polypeptide, and/or recovering or isolating the culture medium containing the expressed variant phenylalanine ammonia lyase polypeptide. In some examples, the methods further provide optionally lysing the transformed host cells after expressing the encoded phenylalanine ammonia lyase polypeptide and optionally recovering and/or isolating the expressed variant phenylalanine ammonia lyase polypeptide from the cell lysate. Methods of making a variant phenylalanine ammonia lyase polypeptide comprise cultivating a host cell transformed with a variant phenylalanine ammonia lyase polypeptide under conditions suitable for the production of the variant phenylalanine ammonia lyase polypeptide and recovering the variant phenylalanine ammonia lyase polypeptide. Typically, recovery or isolation of the phenylalanine ammonia lyase polypeptide is from the host cell culture medium, the host cell or both, using protein recovery techniques that are well known in the art, including those described herein. In some examples, host cells are harvested by centrifugation, disrupted by physical or chemical means, and the resulting crude extract retained for further purification. Microbial cells employed in expression of proteins can be disrupted by any convenient method, including, but not limited to freeze-thaw cycling, sonication, mechanical disruption, and/or use of cell lysing agents, as well as many other suitable methods well known to those skilled in the art.

Variant phenylalanine ammonia lyase enzymes expressed in a host cell can be recovered from the cells and/or the culture medium using any one or more of the techniques known in the art for protein purification, including, among others, lysozyme treatment, sonication, filtration, salting- out, ultra-centrifugation, and chromatography. Suitable solutions for lysing and the high efficiency extraction of proteins from bacteria, such as E. coli, are commercially available under the trade name CelLytic BTM (Sigma-Aldrich). Thus, in some examples, the resulting polypeptide is recovered/isolated and optionally purified by any of a number of methods known in the art. For example, in some examples, the polypeptide is isolated from the nutrient medium by conventional procedures including, but not limited to, centrifugation, filtration, extraction, spray-drying, evaporation, chromatography (e.g., ion exchange, affinity, hydrophobic interaction, chromatofocusing, and size exclusion), or precipitation. In some examples, protein refolding steps are used, as desired, in completing the configuration of the mature protein. In addition, in some examples, high performance liquid chromatography (HPLC) is employed in the final purification steps. For example, in some examples, methods known in the art, find use herein (See e.g., Parry et al. , Biochem. J., 353: 117 [2001]; and Hong et al., Appl. Microbiol. Biotechnol., 73: 1331 [2007]). Indeed, any suitable purification methods known in the art find use herein.

Chromatographic techniques for isolation of the phenylalanine ammonia lyase polypeptide include, but are not limited to reverse phase chromatography high performance liquid chromatography, ion exchange chromatography, gel electrophoresis, and affinity chromatography. Conditions for purifying a particular enzyme will depend, in part, on factors such as net charge, hydrophobicity, hydrophilicity, molecular weight, molecular shape, etc., are known to those skilled in the art. In some examples, affinity techniques find use in isolating the variant phenylalanine ammonia lyase enzymes. For affinity chromatography purification, any antibody which specifically binds the phenylalanine ammonia lyase polypeptide may be used. For the production of antibodies, various host animals, including but not limited to rabbits, mice, rats, etc., may be immunized by injection with the phenylalanine ammonia lyase. The phenylalanine ammonia lyase polypeptide may be attached to a suitable carrier, such as BSA, by means of a side chain functional group or linkers attached to a side chain functional group. Various adjuvants may be used to increase the immunological response, depending on the host species, including but not limited to Freund’s (complete and incomplete), mineral gels such as aluminum hydroxide, surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, keyhole limpet hemocyanin, dinitrophenol, and potentially useful human adjuvants such as BCG (Bacillus Calmette Guerin) and Corynebacterium parvum.

In some examples, the phenylalanine ammonia lyase variants are prepared and used in the form of cells expressing the enzymes, as crude extracts, or as isolated or purified preparations. In some examples, the phenylalanine ammonia lyase variants are prepared as lyophilisates, in powder form (e.g., acetone powders), or prepared as enzyme solutions. In some examples, the phenylalanine ammonia lyase variants are in the form of substantially pure preparations.

In some examples, the phenylalanine ammonia lyase polypeptides are attached to any suitable solid substrate. Solid substrates include but are not limited to a solid phase, surface, and/or membrane. Solid supports include, but are not limited to organic polymers such as polystyrene, polyethylene, polypropylene, polyfluoroethylene, polyethyleneoxy, and polyacrylamide, as well as co-polymers and grafts thereof. A solid support can also be inorganic, such as glass, silica, controlled pore glass (CPG), reverse phase silica or metal, such as gold or platinum. The configuration of the substrate can be in the form of beads, spheres, particles, granules, a gel, a membrane or a surface. Surfaces can be planar, substantially planar, or non-planar. Solid supports can be porous or non-porous, and can have swelling or non-swelling characteristics. A solid support can be configured in the form of a well, depression, or other container, vessel, feature, or location. A plurality of supports can be configured on an array at various locations, addressable for robotic delivery of reagents, or by detection methods and/or instruments.

In some examples, immunological methods are used to purify phenylalanine ammonia lyase variants. In one approach, antibody raised against a variant phenylalanine ammonia lyase polypeptide (e.g., against a polypeptide comprising any of SEQ ID NO: 2, 4, 6, 8, 10, 12 and/or an immunogenic fragment thereof) using conventional methods is immobilized on beads, mixed with cell culture media under conditions in which the variant phenylalanine ammonia lyase is bound, and precipitated. In a related approach, immunochromatography finds use. In some examples, the variant phenylalanine ammonia lyases are expressed as a fusion protein including a non-enzyme portion. In some examples, the variant phenylalanine ammonia lyase sequence is fused to a purification facilitating domain. As used herein, the term "purification facilitating domain" refers to a domain that mediates purification of the polypeptide to which it is fused. Suitable purification domains include, but are not limited to metal chelating peptides, histidine-tryptophan modules that allow purification on immobilized metals, a sequence which binds glutathione (e.g., GST), a hemagglutinin (HA) tag (corresponding to an epitope derived from the influenza hemagglutinin protein; See e.g., Wilson et al., Cell 37:767 [1984]), maltose binding protein sequences, the FLAG epitope utilized in the FLAGS extension/affinity purification system (e.g., the system available from Immunex Corp), and the like. One expression vector contemplated for use in the compositions and methods described herein provides for expression of a fusion protein comprising a polypeptide described herein fused to a polyhistidine region separated by an enterokinase cleavage site. The histidine residues facilitate purification on IMIAC (immobilized metal ion affinity chromatography; See e.g., Porath et al., Prot. Exp. Purif. , 3:263- 281 [1992]) while the enterokinase cleavage site provides a means for separating the variant phenylalanine ammonia lyase polypeptide from the fusion protein. pGEX vectors (Promega) may also be used to express foreign polypeptides as fusion proteins with glutathione S-transferase (GST). In general, such fusion proteins are soluble and can easily be purified from lysed cells by adsorption to ligand-agarose beads (e.g., glutathione-agarose in the case of GST-fusions) followed by elution in the presence of free ligand.

Accordingly, in another example, methods of producing the engineered enzyme polypeptides, where the methods comprise culturing a host cell capable of expressing a polynucleotide encoding the engineered enzyme polypeptide under conditions suitable for expression of the polypeptide are described. In some examples, the methods further comprise the steps of isolating and/or purifying the enzyme polypeptides, as described herein.

Appropriate culture media and growth conditions for host cells are well known in the art. It is contemplated that any suitable method for introducing polynucleotides for expression of the enzyme polypeptides into cells will find use herein. Suitable techniques include, but are not limited to electroporation, biolistic particle bombardment, liposome mediated transfection, calcium chloride transfection, and protoplast fusion.

Another example describes culturing a host cell capable of expressing a polynucleotide encoding the engineered enzyme polypeptide under conditions suitable for expression of the polypeptide. In some examples, the methods further comprise the steps of isolating and/or purifying the enzyme polypeptides, as described herein. Appropriate culture media and growth conditions for host cells are well known in the art. It is contemplated that any suitable method for introducing polynucleotides for expression of the enzyme polypeptides into cells will find use herein. Suitable techniques include, but are not limited to electroporation, biolistic particle bombardment, liposome mediated transfection, calcium chloride transfection, and protoplast fusion.

DEFINITIONS:

The term“amount” herein refers either to the weight of the compounds or to the molar amount of the compounds.

The term“about”, as used herein, is intended to provide flexibility to a numerical range endpoint, providing that a given value may be“a little above” or“a little below” the endpoint accounting for variations one might see in the measurements taken among different instruments, samples, and sample preparations. The term usually means within 10%, preferably within 5%, and more preferably within 1 % of a given value or range.

The term“room temperature” as used herein, unless specified otherwise, means a temperature from 15 to 30 °C, such as from 20 to 30 °C, particularly such as from 20 to 25 °C.

The term“pharmaceutically acceptable salts” or“salt thereof’ refers to salts that can be formed, for example, as acid addition salts, preferably with organic or inorganic acids. For isolation or purification purposes it is also possible to use pharmaceutically unacceptable salts, for example picrates or perchlorates. For therapeutic use, only pharmaceutically acceptable salts or free compounds are employed (where applicable in the form of pharmaceutical preparations), and these are therefore preferred. The salts of the compound of formula (I), and intermediates, as described in the present invention, are preferably pharmaceutically acceptable salts; suitable counter-ions forming pharmaceutically acceptable salts are known in the field. The term “pharmaceutically acceptable” refers to those compounds, materials, compositions, and/or dosage forms which are suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio.

The term“one-pot”“or“one-pot process” means that in a series (i.e. in a succession) of reactions, for example two or more successive reactions, each reaction product is provided for the next reaction without isolation and purification. The one-pot processes defined herein encompass not only a series (i.e. a succession) of reactions conducted in a single reaction vessel, but also a series (i.e. a succession) of reactions conducted in a plurality of reaction vessels (e.g., by transferring the reaction mixture from one vessel to other) without isolation and purification. Preferably, the one-pot process is conducted in a single reaction vessel.

As used in this specification and the appended claims, the singular forms“a”,“an”, and“the” include plural referents unless the context clearly indicates otherwise.

Similarly, “comprise”, “comprises”, “comprising”, “include”, “includes” and “including” are interchangeable and not intended to be limiting.

In the formulae of the present application the term

on a C-sp3 indicates the absolute stereochemistry, either (R) or (S).

The term“enzymatic reaction” refers to those conditions in the phenylalanine ammonia lyase (PAL) catalyzed reaction ( e.g ., ranges of enzyme loading, substrate loading, temperature, pH, solvents, etc.) under which the selected phenylalanine ammonia lyase is capable of converting a substrate compound to a product compound (e.g., conversion of the compound of formula (C3), or salt thereof, to the compound of formula (C4), or salt thereof; or conversion of the compound of formula (C3), or salt thereof, to the compound of formula (C5), or salt thereof, as disclosed herein.

“Loading”, such as in “substrate loading” or“enzyme loading” refers to the concentration or amount of a component in a reaction mixture at the start of the reaction.

The term’’amino donor” as used herein refers to a compound, or a salt, preferably an inorganic salt, able to provide a NH₂ group, when reacted with a starting material, to obtain an amino- compound.

The term “phenylalanine ammonia lysate” (“PAL”) enzymes are enzymes that catalyze the reversible non-oxidative deamination of L-phenylalanine and related compounds such as L-2- amino-3-(2-(benzyloxy)-3-methoxyphenyl)propanoic acid.

The term“wild-type” and“naturally-occurring” refer to the form found in nature. For example a wild-type polypeptide or polynucleotide sequence is a sequence present in an organism that can be isolated from a source in nature and which has not been intentionally modified by human manipulation.

The term“engineered phenylalanine ammonia lyase” or“variant phenylalanine ammonia lyase” refers to a polypeptide sequence exhibiting at least one improved property compared to wild-type Anabaena variabilis phenylalanine ammonia lyase, the improved property comprising an improved production of compound of formula (C4) or a salt thereof, or an improved utilization of the compound of formula (C3), or a salt thereof, and/or an improved production of the compound of formula (C4), or a salt thereof, from the compound of formula (C3). The improved property also comprises an improved production of compound of formula (C5) or a salt thereof, or an improved utilization of the compound of formula (C3), or a salt thereof, and/or an improved production of the compound of formula (C5), or a salt thereof, from the compound of formula (C3) or a salt thereof.

The term “stereoselectivity” refers to the preferential formation in a chemical or enzymatic reaction of one stereoisomer over another. Stereoselectivity can be partial, where the formation of one stereoisomer is favored over the other, or it may be complete where only one stereoisomer is formed. When the stereoisomers are enantiomers, the stereoselectivity is referred to as enantioselectivity, the fraction (typically reported as a percentage) of one enantiomer in the sum of both. It is commonly alternatively reported in the art (typically as a percentage) as the enantiomeric excess (“e.e.”) calculated therefrom according to the formula [major enantiomer - minor enantiomer]/[major enantiomer + minor enantiomer]. Where the stereoisomers are diastereoisomers, the stereoselectivity is referred to as diastereoselectivity, the fraction (typically reported as a percentage) of one diastereomer in a mixture of two diastereomers, commonly alternatively reported as the diastereomeric excess (“d.e.”). Enantiomeric excess and diastereomeric excess are types of stereomeric excess.

The term“regioselectivity” and“regioselective reaction” refer to a reaction in which one direction of bond making or breaking occurs preferentially over all other possible directions. Reactions can completely (100%) regioselective if the discrimination is complete, substantially regioselective (at least 75%), or partially regioselective (x%, wherein the percentage is set dependent upon the reaction of interest), if the product of reaction at one site predominates over the product of reaction at other sites.

The term“recombinant,”“engineered,”“non-naturally occurring,” and“variant,” when used with reference to a cell, nucleic acid, or polypeptide, refers to a material, or a material corresponding to the natural or native form of the material, that has been modified in a manner that would not otherwise exist in nature. In some embodiments, the cell, nucleic acid or polypeptide is identical a naturally occurring cell, nucleic acid or polypeptide, but is produced or derived from synthetic materials and/or by manipulation using recombinant techniques. Non-limiting examples include, among others, recombinant cells expressing genes that are not found within the native (non recombinant) form of the cell or express native genes that are otherwise expressed at a different level. The term “percent (%) sequence identity” is used herein to refer to comparisons among polynucleotides or polypeptides, and are determined by comparing two optimally aligned sequences over a comparison window, wherein the portion of the polynucleotide or polypeptide sequence in the comparison window may comprise additions or deletions (i.e. , gaps) as compared to the reference sequence for optimal alignment of the two sequences. The percentage may be calculated by determining the number of positions at which the identical nucleic acid base or amino acid residue occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the window of comparison and multiplying the result by 100 to yield the percentage of sequence identity. Alternatively, the percentage may be calculated by determining the number of positions at which either the identical nucleic acid base or amino acid residue occurs in both sequences or a nucleic acid base or amino acid residue is aligned with a gap to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the window of comparison and multiplying the result by 100 to yield the percentage of sequence identity. Those of skill in the art appreciate that there are many established algorithms available to align two sequences. Optimal alignment of sequences for comparison can be conducted by any suitable method, including, but not limited to the local homology algorithm of Smith and Waterman (Smith and Waterman, Adv. Appl. Math., 2:482 [1981]), by the homology alignment algorithm of Needleman and Wunsch (Needleman and Wunsch, J. Mol. Biol., 48:443 [1970]), by the search for similarity method of Pearson and Lipman (Pearson and Lipman, Proc. Natl. Acad. Sci. USA 85:2444 [1988]), by computerized implementations of these algorithms (e.g., GAP, BESTFIT, FASTA, and TFASTA in the GCG Wisconsin Software Package), or by visual inspection, as known in the art. Examples of algorithms that are suitable for determining percent sequence identity and sequence similarity include, but are not limited to the BLAST and BLAST 2.0 algorithms, which are described by Altschul et al. (See Altschul et al., J. Mol. Biol., 215: 403-410 [1990]; and Altschul et al., Nucl. Acids Res., 3389-3402 [1977], respectively). Software for performing BLAST analyses is publicly available through the National Center for Biotechnology Information website. This algorithm involves first identifying high scoring sequence pairs (HSPs) by identifying short words of length W in the query sequence, which either match or satisfy some positive-valued threshold score T when aligned with a word of the same length in a database sequence. T is referred to as, the neighborhood word score threshold (See, Altschul et al., supra). These initial neighborhood word hits act as seeds for initiating searches to find longer HSPs containing them. The word hits are then extended in both directions along each sequence for as far as the cumulative alignment score can be increased. Cumulative scores are calculated using, for nucleotide sequences, the parameters M (reward score for a pair of matching residues; always >0) and N (penalty score for mismatching residues; always <0). For amino acid sequences, a scoring matrix is used to calculate the cumulative score. Extension of the word hits in each direction are halted when: the cumulative alignment score falls off by the quantity X from its maximum achieved value; the cumulative score goes to zero or below, due to the accumulation of one or more negative-scoring residue alignments; or the end of either sequence is reached. The BLAST algorithm parameters W, T, and X determine the sensitivity and speed of the alignment. The BLASTN program (for nucleotide sequences) uses as defaults a wordlength (W) of 11 , an expectation (E) of 10, M=5, N=-4, and a comparison of both strands. For amino acid sequences, the BLASTP program uses as defaults a word length (W) of 3, an expectation (E) of 10, and the BLOSUM62 scoring matrix (See, Henikoff and Henikoff, Proc. Natl. Acad. Sci. USA 89:10915 [1989]). Exemplary determination of sequence alignment and % sequence identity can employ the BESTFIT or GAP programs in the GCG Wisconsin Software package (Accelrys, Madison Wl), using default parameters provided.

The term“control sequence” includes all components, which are necessary or advantageous for the expression of a polynucleotide and/or polypeptide of the present invention. Each control sequence may be native or foreign to the nucleic acid sequence encoding the polypeptide. Such control sequences include, but are not limited to, a leader, polyadenylation sequence, propeptide sequence, promoter sequence, signal peptide sequence, initiation sequence and transcription terminator. At a minimum, the control sequences include a promoter, and transcriptional and translational stop signals. The control sequences may be provided with linkers for the purpose of introducing specific restriction sites facilitating ligation of the control sequences with the coding region of the nucleic acid sequence encoding a polypeptide.

“Operably linked” is defined herein as a configuration in which a control sequence is appropriately placed (i.e., in a functional relationship) at a position relative to a polynucleotide of interest such that the control sequence directs or regulates the expression of the polynucleotide and/or polypeptide of interest.

“Promoter sequence” refers to a nucleic acid sequence that is recognized by a host cell for expression of a polynucleotide of interest, such as a coding sequence. The promoter sequence contains transcriptional control sequences, which mediate the expression of a polynucleotide of interest. The promoter may be any nucleic acid sequence which shows transcriptional activity in the host cell of choice including mutant, truncated, and hybrid promoters, and may be obtained from genes encoding extracellular or intracellular polypeptides either homologous or heterologous to the host cell.

The phrase“suitable reaction conditions” refers to those conditions in the enzymatic conversion reaction solution (e.g., ranges of enzyme loading, substrate loading, temperature, pH, buffers, co-solvents, etc.) under which a phenylalanine ammonia lyase polypeptide of the present invention is capable of converting a substrate to the desired product compound. Some exemplary “suitable reaction conditions” are provided herein.

ABBREVIATIONS

AcOH Acetic acid

br Broad

d Doublet

DMF Dimethylformamide

DMSO Dimethylsulfoxide

EtOAc Ethyl acetate

H2SO4 Sulfuric acid

HBr Hydrobromic acid

HCI Hydrochloric acid

J Coupling constant

LG Leaving group

M Molar

m multiplet

MeTHF Methyl tetrahydrofuran

MTBE Methyl terf-butyl ether

NMR Nuclear magnetic resonance

ppm Parts per million

q quartet

quint quintet

s singlet

t triplet

TFA Trifluoroacetic acid

TPGS Tocopherol polyethylene glycol succinates

Wt% Weight percent

EXAMPLES

The skilled person will appreciate that the general synthetic routes detailed above show common reactions to transform the starting materials as required. When specific reactions are not provided the skilled person will know that such reactions are well known to those skilled in the art and appropriate conditions considered to be within the skilled person’s common general knowledge. The starting materials are either commercially available compounds or are known compounds and can be prepared from procedures described in the organic chemistry art.

Compounds as described herein, in free form, may be converted into salt form and vice versa, in a conventional manner understood by those skilled in the art. The compounds in free or salt form can be obtained in the form of hydrates or solvates containing a solvent used for crystallization. Compounds described herein can be recovered from reaction mixtures and purified in a conventional manner. Isomers, such as stereoisomers, may be obtained in a conventional manner, e.g. by fractional crystallization or asymmetric synthesis from correspondingly asymmetrically substituted, e.g. optically active, starting materials. The various starting materials, intermediates, and compounds of the preferred embodiments may be isolated and purified, where appropriate, using conventional techniques such as precipitation, filtration, crystallization, evaporation, distillation, and chromatography. Unless otherwise stated. Salts may be prepared from compounds by known salt-forming procedures.

The compounds described herein can be prepared, e.g. using the reactions and techniques described below and in the examples. The reactions may be performed in a solvent appropriate to the reagents and materials employed and suitable for the transformations being effected. It will be understood by those skilled in the art of organic synthesis that the functionality present on the molecule should be consistent with the transformations proposed. This will sometimes require a judgment to modify the order of the synthetic steps or to select one particular process scheme over another in order to obtain a desired compound of the invention. In the embodiments herein and illustrated in the Examples, various ranges of suitable reaction conditions that can be used in the processes, including but not limited, to ranges of amino donor, pH, temperature, buffer, solvent system, substrate loading, enzyme (phenylalanine ammonia lyase) loading, and reaction time. Further suitable reaction conditions for carrying out the claimed phenylalanine ammonia lyase process can be readily optimized in view of the guidance provided herein by routine experimentation that includes, but is not limited to, contacting the phenylalanine ammonia lyase and substrate compound under experimental reaction conditions of concentration, pH, temperature, solvent conditions, and detecting the product compound.

MEASUREMENTS METHODS

Proton-NMR: measurements were performed on Bruker 400MHz spectrometer. Chemical shifts (d-values) are reported in ppm downfield and the spectra splitting pattern are designated as singlet (s), doublet (d), triplet (t), quartet (q), quintet (quint), multiplet, unresolved or overlapping signals (m), broad signal (br). Deuterated solvents are given in parentheses. LCMS: measurements were performed on a Acquity UPLC/SQD MS (ESI) using a ACQUITY

UPLC® HSS T3 1 8pm column with eluents water + 0.05 % FA + 3.75 mM AA and acetonitrile + 0.04 % FA at a column temperature of 60 °C

Example 1 : Synthesis of (S)-2-amino-3-(2-(benzyloxy)-3-methoxyphenyl)propanoic acid, or a salt thereof (C4)

Compound of formula (C3) (5 g, 1.0 eq.) was dissolved in DMSO (10 ml_) and transferred to the addition funnel. A 9.7 M ammonium carbamate solution (150 ml_) was mixed with DMSO (5 ml_). The enzyme PAL-128 (2 g, #Codexis) was suspended in 10 mL of the ammonium carbamate/DMSO solution and transferred back to the ammonium carbamate solution. The mixture was warmed to 35 ± 3 °C and the mixture containing compound of formula (C3) was added over 2 hours onto the mixture. After the addition, the mixture was stirred for 20 hours at 35 ± 3 °C, then cooled within 6 hours to 20 °C and stirred at this temperature for an additional 16 hours. The mixture was then added to concentrated aqueous HCI (1 10 mL) and MeTHF (200 mL). A strong exotherm and gas evolution were observed. After the addition, the pH was adjusted to 2.0 ± 0.1 using concentrated aqueous HCI (4.5 mL). The mixture was warmed to 20 °C, MeTHF (100 mL) was added, followed by sodium chloride (NaCI) (43 g). The phases were separated and the aqueous layer was extracted with MeTHF (2 x 200 mL). The organic phases were filtered over a K-900 filter. After filtration, a biphasic mixture was obtained, which was washed with saturated aqueous NaCI (75 mL). The phases were separated and the organic layer was concentrated at 40 °C to approximately 50 mL. Then the layer was diluted with MeTHF (100 mL), and concentrated again to approximately 50 mL, at 40 °C. The thus obtained suspension was diluted with TBME (100 mL) over 2 hours, under simultaneous cooling to 20 °C. The mixture was stirred for 30 minutes, filtered and the filtercake washed with TBME (40 mL). The filtercake was dried at 50 °C and 15 mbar to obtain the compound of formula (C4) (5.02 g, 84wt% assay, 69% yield, >99% e.e., as an HCI salt) as a white solid. ¹H NMR (400 MHz, (DMSO-d6): S = 3.03 (dd, J = 13.8, 7.3 Hz, 1 H), 3.14 (dd, J = 13.8, 7.5 Hz, 1 H), 3.84 (s, 3H), 3.98 (t, J = 7.4 Hz, 1 H), ), 4.98 (dd, J = 1 1.0, 11.0 Hz, 2H), 6.85 (dd, J = 6.5, 2.7 Hz, 1 H), 6.97 - 7.08 (m, 2H), 7.30 - 7.42 (m, 3H), 7.46 - 7.55 (m, 2H), 8.50 (br. s, 3H), 13.61 (br. s, 1 H). ESI-MS: m/z: 302.1 ([M + H]⁺, calcd for CI₇H_2ON0₄ ⁺: 302.1). Example 2: Synthesis of (S)-5-(benzyloxy)-6-methoxy-1 ,2,3,4-tetrahydroisoquinoline-3- carboxylic acid

Compound of formula (C4), or a salt thereof, in this case the HCI salt (1.9 g, 1.0 eq) was mixed with paraformaldehyde (0.19 g, 96 wt%, 1.1 eq), and then suspended in acetic acid (19 ml_). The mixture was heated to 50 °C, was stirred for 2 hours, then cooled to 20 °C and stirred for 30 minutes. Then the mixture was filtered and the filter cake was washed with acetone (3 x 4 ml_). The wet product was dried in the vacuum oven at 50 °C, at 10 - 20 mbar, to afford the compound of formula (C5) as a white solid (1.4 g, 71 %, as an HCI salt). ¹ H NMR (400 MHz, DMSO-de) d = 2.78 - 2.94 (m, 1 H), 3.25 (dd, J = 17.4, 5.3 Hz, 1 H), 3.85 (s, 3H), 4.16 - 4.35 (m, 3H), 4.99 (d, J = 2.6 Hz, 2H), 7.01 (d, J = 8.6 Hz, 1 H), 7.07 (d, J = 8.6 Hz, 1 H), 7.31 - 7.49 (m, 5H), 9.59 (br. s, 2H), 14.18 (br. s, 1 H).

Example 3: Synthesis of (S)-5-(benzyloxy)-6-methoxy-1 ,2,3,4-tetrahydroisoquinoline-3- carboxylic acid

Method 1 : Compound of formula (C3) (5.0 g, 1.0 eq.) was dissolved in DMSO (8 ml_) and transferred to the addition funnel. A 8.4 M ammonium carbamate solution (50 ml_) was mixed with DMSO (2 ml_). The enzyme PAL-128 (2 g, #Codexis) was suspended in 10 mL of the ammonium carbamate/DMSO solution and transferred back to the ammonium carbamate solution. The mixture was warmed to 35 ± 3 °C and the C3 solution was added over 2 h. After the addition, the mixture was stirred for 20 hours at 35 ± 3 °C, then cooled within 6 hours to 20 °C and stirred at this temperature for a total of 72 hours. The reaction mixture was then added to a mixture of 50% H2SO4 (34 g) and toluene (60 mL) at 0 - 5 °C. The pH of the resulting suspension was adjusted to 2.0 using concentrated H2SO4 (17.4 g) and filtered over K-900. The filtercake was rinsed with 2 M H2SO4 (30 mL). TBME (20 mL) was added. The organic phase in the mother liquor was separated and the combined aqueous phases were treated with paraformaldehyde (0.52 g, 1 eq.). The mixture was warmed to 60 °C and stirred for 22 hours. The mixture was then cooled to 10 °C and the pH adjusted to using NaOAc (14.5 g). The resulting suspension was filtered and the filtercake was washed with H₂0 (25 ml_), H2O with 10% EtOH (50 ml_) and acetone to obtain a compound of formula (C5) as a white solid (2.5 g, 45%, >99% e.e.). ¹H NMR (400 MHz, CD3CO2D): d = 2.87 (dd, J = 17.5, 1 1.0 Hz, 1 H), 3.35 (dd, J = 17.6, 5.3 Hz, 1 H), 3.75 (s, 3H), 4.04 (dd, J = 11.0, 5.4 Hz, 1 H), 4.28 (dd, J = 15.4, 15.4 Hz, 2H), 4.87 - 4.96 (m, 2H), 6.74 - 6.88 (m, 2H), 7.12 - 7.25 (m, 3H), 7.28 - 7.35 (m, 2H); ESI-MS: mlr 314.3 ([M + H]⁺, calcd for CISH2ON04⁺: 314.4).

Method 2: An emulsion of compound of formula (C3) (10 g, 1.0 eq.) and enzyme PAL-130 (0.5 g, #Codexis) in aqueous ammonium carbonate (ca. 10 M, 70 mL, pH ca. 10) was warmed to 45 °C and stirred for 8 hours. Then the reaction was cooled to 20 °C in 8 hours and stirred for a total reaction time of 66 hours (68% conversion by HPLC). A mixture of 1 -butanol/xylenes (45 g, 7:3 w/w) was added and the mixture was warmed to 25 °C. The biphasic mixture is filtered over K- 900 and the phases were separated. The aqueous layer was extracted one more time with 1- butanol/xylenes (45 g, 7:3 w/w). The combined organic layers were evaporated under reduced pressure to about 2/3 of the original volume, until precipitation was observed. Xylenes (130 g) and 1 M aqueous H2SO4 (50 mL) were added. The phases were separated and the organic layer was extracted with a second portion of 1 M aqueous H2SO4 (20 mL). The combined aqueous layers were treated with para-formaldehyde (2.64 g), warmed to 50 °C for 16 hours. Then the mixture was cooled to 20 °C, diluted with H2O (30 g) and the pH was adjusted to 5.5 with 30wt% aqueous NaOH solution (18.2 g). The suspension was filtered and the filter cake washed with H2O (2 x 30 g) and acetone (2 x 30 g). The wet product was dried at 50 °C under vacuum to afford compound of formula (C5) (6.9 g, 63%) as a white solid. ¹ H NMR (400 MHz, CD3CO2D): d = 2.87 (dd, J = 17.5, 11.0 Hz, 1 H), 3.35 (dd, J = 17.6, 5.3 Hz, 1 H), 3.75 (s, 3H), 4.04 (dd, J = 11.0, 5.4 Hz, 1 H), 4.28 (dd, J = 15.4, 15.4 Hz, 2H), 4.87 - 4.96 (m, 2H), 6.74 - 6.88 (m, 2H), 7.12

- 7.25 (m, 3H), 7.28 - 7.35 (m, 2H); ESI-MS: mlr 314.3 ([M + H]⁺, calcd for Ci₈H₂oN0₄ ⁺: 314.4).

Method 3: To an emulsion of compound of formula (C3) (20 g, 1.0 eq.) in ammonium carbonate (120 mL, 9.3 M, prepared by suspending ammonium carbonate (70 g) in H2O (120 mL) and adjusting the pH to 10 with 25wt% aqueous NH₃ (40 g)) was added a turbid solution of enzyme PAL-130 (1 g, #Codexis) in a 1 : 1 mixture of the aqueous ammonium carbonate solution above (5 mL) and H2O (5 mL). The resulting turbid emulsion was warmed to 45 °C, and stirred for 8 hours. Then the mixture was cooled to 20 °C in 8 hours, and stirred for a total reaction time of 96 hours (76% conversion by HPLC). MeOH (60 mL) was added and the mixture was stirred for 1 hour. H2O (60 mL) was then added. The 60 mL liquid was distilled out of the reactor (70 °C, 300

- 600 mbar). H2O (60 mL) was added and the 60 mL liquid was distilled out of the reactor. This procedure is repeated one more time. The resulting suspension was cooled to 40 °C and 2.5 M aqueous H2SO4 (37.7 g) was added until pH < 1.2 (1.08 measured). The resulting mixture was cooled to 25 °C and stirred for 16 hours. The mixture was filtered over a K-900 filter plate and the filter cake re-slurried with 1 M H2SO4 (50 g) twice. The combined mother and wash liquors were treated with para-formaldehyde (3.2 g) and warmed to 50 °C for 16 hours. Then, the mixture was cooled to 40 °C, and the pH was adjusted to 5.5 with 50wt% aqueous NaOH solution (26.4 g). The suspension was cooled to 20 °C, filtered and the filter cake was washed with H2O (2 x 60 g) and acetone (2 x 60 g). The wet product was dried at 50 °C under vacuum to afford compound of formula (C5) (15 g, 68%) as a white solid. ¹H NMR (400 MHz, CD₃CO2D): d = 2.87 (dd, J = 17.5, 11.0 Hz, 1 H), 3.35 (dd, J = 17.6, 5.3 Hz, 1 H), 3.75 (s, 3H), 4.04 (dd, J = 1 1.0, 5.4 Hz, 1 H),

4.28 (dd, J = 15.4, 15.4 Hz, 2H), 4.87 - 4.96 (m, 2H), 6.74 - 6.88 (m, 2H), 7.12 - 7.25 (m, 3H),

7.28 - 7.35 (m, 2H); ESI-MS: m/z: 314.3 ([M + H]⁺, calcd for Ci₈H₂oN0₄ ⁺: 314.4).

Claims

1. A process for preparing a compound of formula (C4),

or a salt thereof,

the process comprising the steps of reacting a compound of formula (C3),

salt thereof,

salt or solvate thereof.

2. The process according to claim 1 , wherein the amino donor is selected from the group consisting of ammonium carbamate, ammonia, ammonium salts and mixtures thereof.

3. The process according to claims 1 or 2, wherein the amino donor is ammonium carbamate or ammonia.

4. The process according to any one of claims 1 to 3, wherein the engineered phenylalanine ammonia lyase has an amino acid sequence selected from the list consisting of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, and SEQ ID N° 12.

5. The process according to any one of claims 1 to 4, wherein the solvent is selected from the group consisting of DMSO, propylene glycol, TPGS-750-M, glycerol, ethylene glycol, acetonitrile, heptane, isopropanol, DMF, toluene, THF, MTBE, EtOAc, acetone, MeTHF, and mixtures thereof.

6. The process according to claim 5, wherein the solvent is selected from the group consisting of DMSO, propylene glycol, TPGS-750-M, glycerol, ethylene glycol, acetonitrile, heptane, and mixtures thereof.

7. A process for preparing a compound of formula (C5), or a salt or solvate thereof, the process comprising the steps of

i. reacting a compound of formula (C3)

salt thereof,

with an engineered phenylalanine ammonia lyase (PAL), and an amino donor, optionally in the presence of a solvent, as defined in claim 1 ,

ii. adding an acid, and then adding an aldehyde derivative, to obtain a compound of formula (C5)

salt or a solvate thereof.

8. The process according to claim 7, wherein the aldehyde derivative is selected from the group consisting of paraformaldehyde, formaldehyde, 2,4,6-trimethyl-1 ,3,5-trioxane, urotropine and formaline.

9. The process according to claim 7, wherein the acid is selected from the group consisting of acetic acid, HCI, HBr, H2SO4, TFA, citric acid, formic acid, phosphoric acid, mixtures thereof, and buffer solutions of those acids.

10. A process for preparing a compound of formula (I),

salt, or a solvate thereof,

the process comprising the steps of: i. reacting a compound of formula (C3), or a salt thereof, to prepare a compound of formula (C4), or a salt thereof, according to claims 1 to 6

11. A process for preparing a compound of formula (I),

salt, or a solvate thereof,

the process comprising the steps of:

i. reacting a compound of formula (C3), or a salt thereof, to prepare a compound of formula (C5), or a salt thereof, according to claims 7 to 9

ii. further reacting the compound of formula (C5), or a salt thereof, to obtain a compound of formula (I), or a salt, or a solvate thereof.

12. A process for preparing a pharmaceutical composition, the process comprising the process according to any one of the claims 1 to 11 and mixing the obtained compound of formula (I), or a salt, or a solvate thereof, with a pharmaceutically acceptable excipient.