WO2013117251A1

WO2013117251A1 - Method for enzymatic redox cofactor regeneration

Info

Publication number: WO2013117251A1
Application number: PCT/EP2012/067781
Authority: WO
Inventors: Ortwin Ertl; Nicole STAUNIG; Marta SUT; Bernd Mayer
Original assignee: Annikki Gmbh
Priority date: 2012-02-07
Filing date: 2012-09-12
Publication date: 2013-08-15

Abstract

Disclosed is a method for enzymatically regenerating the redox confactors NAD⁺/NADH und NADP⁺/NADPH in a one-pot reaction. In said method, one of the two redox cofactors is obtained in the reduced form thereof while the other redox cofactor is obtained in the oxidized form thereof as a result of at least two additional enzymatically catalyzed redox reactions (product forming reactions) taking place in the same reaction batch. The disclosed method is characterized in that a) oxygen or a compound of general formula R₁C(O)COOH is reduced during the regeneration reaction converting the reduced cofactor back into the original oxidized form thereof, and b) a compound of general formula R₂CH(OH)R₃ is oxidized during the regeneration reaction converting the oxidized cofactor back into the original reduced form thereof, R₁, R₂, and R₃ in the compounds having different meanings.

Description

Process for the enzymatic regeneration of redox cofactors

Background of the invention

The present invention relates to a process for the enzymatic regeneration of the redox cofactors NAD ⁺ / NADH and NADP ⁺ / NADPH in a one-pot reaction, wherein as a result of at least two further running in the same reaction enzymatically catalyzed redox reactions (= product formation reactions) of the two

Redoxkofaktoren in its reduced form is obtained and the other in its oxidized form.

State of the art

Enzyme-catalyzed redox reactions are used in industrial processes, for example in the preparation of chiral alcohols, α-amino acids and α-hydroxy acids. The majority of enzymes used in industrial redox reactions use cofactors such as NADH or NADPH. Among the enzymatic redox reactions, those of particular interest are those in which the redox cofactors are restored by in situ cofactor regeneration systems. The reason for this is that the use of only catalytic amounts of expensive cofactors (NAD (P) ⁺ / NAD (P) H) is possible. The accessibility of suitable dehydrogenases and other enzymes has led to the development of various cofactor regeneration systems.

The regeneration systems described so far could be classified as:

enzyme-coupled, substrate-coupled, in vivo (natural cofactor regeneration systems in living organisms), photochemically, chemically or electro-enzymatically. The method described here relates to an enzyme-linked regeneration system. Advantages of enzyme-coupled systems are the high selectivity, the applicability for the production of different products and the high reuse rate of the total turnover number (TTN).

In the mid-1990s, a first industrial process using an enzyme-coupled cofactor regeneration system on a ton scale was applied. In In this process, formaldehydrogenase from Candida boidinii was used. The hitherto known industrial processes usually use a redox enzyme for

Product synthesis and another enzyme for cofactor regeneration.

A distinction must be made between processes in which two or more enzymatic redox reactions involved in product formation and two enzymatic systems for cofactor regeneration (simultaneously or sequentially) take place in one reaction batch, without any intermediate product being isolated. Recently, such enzymatic

Cascade reactions - referred to herein as one-pot reactions - significant

Attention attracts as it effectively operating costs, operating time and

Reduce environmental impact. In addition, enzymatic cascades of redox reactions allow for transformations that are not easily implemented by classical chemical methods.

However, it is a challenge to carry out several reactions (oxidation and reduction) simultaneously in a one-pot reaction with parallel cofactor regeneration, since very divergent reaction conditions are often necessary for the individual transformations. To date, very few one-pot experiments have been performed involving oxidation and reduction reactions with associated cofactor regeneration systems.

The literature (Advanced Synth. Catal., 2008, Volume 351, Issue 9, pl303-1311) has attempted a one-pot reaction using 7 a-

Hydroxysteroid dehydrogenase (HSDH), 7ß-HSDH and 12a-HSDH. In the process, both regioselective and stereoselective oxidation was performed at positions 7 and 12 of cholic acid, followed by a regio- and

stereoselective reduction at position 7. In the process, the cofactor regeneration system used was a lactate dehydrogenase (NAD ⁺ -dependent) as well as a glucose dehydrogenase (NADP ⁺ -dependent). Cosubstrates used were pyruvate and glucose. Although this process was originally aimed at a true one-pot process, ultimately oxidation and reduction reactions were carried out separately. The division of oxidative and reductive steps was carried out either in a so-called "TeebeuteP'-reactor or in the membrane reactor. This division was necessary to avoid the production of by-products due to the low cofactor selectivity of NADPH glucose dehydrogenase. However, in the one-pot reaction, glucose dehydrogenase NADP ⁺ partially reversed NAD ⁺ , hindering oxidation. In the process described, only 12.5 mM (-0.5%) of the substrate cholic acid was used, making the process economically uninteresting.

It has also been described an attempt to perform the deracemization of racemates of secondary alcohols via a prochiral ketone as an intermediate using a one-pot system (J. Am. Chem. Soc, 2008, volume 130, pl3969-13972). The deracemization of secondary alcohols was over two

Alcohol dehydrogenases (S- and R-specific) with different cofactor specificity achieved. In the system, NADP was regenerated by NADPH oxidase (hydrogen peroxide producing) and NADH by formate dehydrogenase. The co-substrates used were formate and oxygen. In the system were 4 enzymes without

Distribution of oxidative and reductive steps used. A disadvantage of the method is the very low concentration of the substrate used of 0.2-0.5%, which is not suitable for industrial purposes.

Another one-pot system has been described in WO 2009/121785 A2. By doing

Method, a stereoisomer of an optically active secondary alcohol was oxidized to the ketone and then reduced to the corresponding optical antipode, with two

Alcohol dehydrogenases with opposite stereoselectivities and different cofactor specificities were used. The cofactors were regenerated by means of a so-called "hydride transfer system" using only one additional enzyme To regenerate the cofactors, various enzymes, e.g.

Formate dehydrogenase, glucose dehydrogenase, lactate dehydrogenase. A disadvantage of this method is the low concentration of the substrates used.

The disadvantage of the hitherto known enzymatic one-pot process with cofactor regeneration systems is overall the very low substrate concentration, which is uneconomical for industrial processes. In contrast, many individual enzymatic redox reactions using cofactor regeneration systems are already known. The experiments were performed with whole microorganisms, cell lysates or isolated enzymes with simultaneous

NAD (P) H or NAD (P) ⁺ regeneration described. Known enzymatic cofactor regeneration systems for individual redox reactions include, for example

Formate dehydrogenase for NADH (formate as cosubstrate), alcohol dehydrogenase from Pseudomonas sp. for NADH (2-propanol as cosubstrate), hydrogenase for NADH and NADPH (H ₂ as cosubstrate), glucose-6-phosphate dehydrogenase from L. mes enter much for NADPH (glucose-6-phosphate as cosubstrate), glucose dehydrogenase for NADH and NADPH (Glucose as cosubstrate), NADH oxidase for NADH (0 ₂ as cosubstrate) and phosphite dehydrogenase for NADH (phosphite as cosubstrate).

One application example of such individual redox reactions is the preparation of chiral hydroxy compounds starting from corresponding prochiral keto compounds. In these methods, the cofactor is regenerated by means of an additional enzyme. These methods have in common that they represent an isolated reduction reaction and regenerate NAD (P) H (see, for example, EP 1 152 054).

Enzymatic methods using hydroxysteroid dehydrogenases coupled with cofactor regeneration system that run at higher substrate concentrations (> 1) have been described (EP 1 731 618; WO 2007/118644; Appl. Microbiol.

Biotechnol., 2011 Volume 90 pl27-135). In the procedures the cofactors became

NAD (P) H or NAD (P) by various enzymes such as

Lactate dehydrogenase (pyruvate as cosubstrate), alcohol dehydrogenase from T. brockii (isopropanol as cosubstrate), alcohol dehydrogenase from L. brevis, L. minor, Leuconostoc carnosum, T. ethanolicus, Clostridium beijerinckii regenerated. However, these known methods relate only to the isolated individual reactions for the oxidation of

Hydroxy compound or for the reduction of oxo compound.

A cofactor regeneration system for NADH using malate dehydrogenase ("malate enzyme") has been previously described (Can, J. Chem., Eng, 1992, Volume 70, p 306-312), and has been published in the publication for the reductive amination of pyruvate Used alanine dehydrogenase. The pyruvate formed during cofactor regeneration was subsequently used in the product-forming reaction.

WO 2004/022764 also describes regenerating NADH by malate dehydrogenase. Unlike in the previously described publication, the pyruvate formed in the oxidative decarboxylation of malate was discontinued.

An example of enzymatic reduction of D-xylose to xylitol with cofactor regeneration system has been described (FEBS J., 2005, Volume 272, p 3816-3827). The cofactor regeneration enzyme was an NADPH-dependent mutant of

Phosphite dehydrogenase from Pseudomonas sp. used. Again, this is an individual reaction to product formation.

Other examples of enzymatic preparation of chiral enantiomerically enriched organic compounds such as alcohols or amino acids have been described (Organic Letters, 2003, Volume 5, pp. 3649-3650, U.S. Patent No. 7,163,815, Biochem. Eng. J., 2008, Volume 39 (2 ) p 319-327, EP 1 285 962). In the systems, the Kofakor regeneration enzyme used was an NAD (P) H-dependent oxidase from Lactobacillus brevis or Lactobacillus sanfranciscensis. The experiments are also individual reactions for product formation.

In WO 2011/000693 a 17beta-hydroxysteroid dehydrogenase and a method is described, with which it is possible to perform redox reactions at position 17 of 4-androstene-3,17-dione. Again, this is an isolated reduction reaction. The advantages of a one-pot reaction, such as, for example, the above individual oxidation or reduction reactions, are eliminated. Profitability through time and money

Material savings and better sales through enzymatic cascade reactions.

Task and description of the procedure

The object of the present invention was to provide a process for regenerating the redox cofactors NAD ⁺ / NADH and NADP ⁺ / NADPH to thereby have two or more perform enzymatically catalyzed redox reactions in a reaction mixture economically.

This object is achieved according to the present invention in a method of the type mentioned in that a process for the enzymatic regeneration of the redox cofactors NAD ⁺ / NADH and NADP ⁺ / NADPH in a one-pot reaction, wherein as a result of at least two further in the same reaction mixture expired enzymatically catalyzed redox reactions (product formation reactions) of one of the two

Redox cofactors in its reduced form and the other in its oxidized form,

is provided, which is characterized in that

a) in the regeneration reaction, the reduced cofactor back in his

original oxidized form, oxygen or a compound of the

general formula

wherein Ri is a straight-chain or branched-chain (Ci-C ₄ ) alkyl group or for (Ci-C ₄ ) -Carboxyalkylgruppe, is reduced, and

b) in the regeneration reaction, the oxidized cofactor in his

converted original reduced form, a (C ₄ -Cg) cycloalkanol or a

Compound of the general formula

wherein R ₂ and R _{3 are} independently selected from the group consisting of H, (QC ^ -alkyl, wherein alkyl is straight-chain or branched, (Ci-Cö ^ alkenyl, wherein alkenyl is straight-chain or branched and contains one to three double bonds, aryl, especially C _Ö -C ₁₂ aryl, carboxyl, or (Ci-C4) carboxyalkyl, in particular, cycloalkyl, including _C3 -CG cycloalkyl,

is oxidized. A method provided in accordance with the present invention is also referred to herein as a "method according to (the present invention)".

In a further aspect, the present invention provides a process according to the present invention for the enzymatic regeneration of the redox cofactors NAD ⁺ / NADH and NADP ⁺ / NADPH in a one-pot reaction, resulting in at least two further enzymatically catalyzed redox reactions occurring in the same reaction mixture

(= Product-forming reactions) of one of the two redox cofactors in its reduced form is obtained and the other in its oxidized form, available, characterized in that

a) in the case of regeneration of the oxidized cofactor, a compound of the general formula I is reduced,

wherein Ri is a substituted or unsubstituted C 1 -C 4 alkyl group, and b) a compound of the general one in the regeneration of the reduced cofactor

Formula II is oxidized,

wherein R ₂ and R _{3 are} independently selected from the group consisting of

1) -H,

2) - (C ₁ -C _ö) -alkyl, wherein alkyl is straight or branched,

3) - (C ₁ -C _ö) -alkenyl, wherein alkenyl is straight or branched chain and

optionally contains up to three double bonds,

4) -cycloalkyl, in particular C ₃ -Cg -cycloalkyl,

5) -aryl, in particular C ₆ -C ₁₂ aryl,

6) - (C ₁ -C ₄ ) carboxyalkyl, if compound I is pyruvate,

optionally also carboxyl. In a further aspect R in a method according to the present invention ₂ and R _{3 are} independently selected from the group consisting of H, (C ₁ -C _ö) -alkyl, wherein alkyl is straight chain or branched (C ₁ -C _ö) Alkenyl, wherein alkenyl is straight-chain or branched and contains one to three double bonds, aryl, in particular C ₆ -C ₁₂ aryl, carboxyl, or (C ₁ -C ₄ ) -carboxyalkyl.

Compared to the prior art, a process according to the present invention represents a substantial improvement in processes in which compounds are both enzymatically oxidized and reduced, as this makes it possible to obtain the necessary oxidation and reduction reactions as well as the associated reactions for cofactor regeneration to run a reaction and at the same time much higher

Use substrate concentrations than is the case in the prior art.

In a method according to the invention the cofactors NADH and NADPH are used. NAD ⁺ denotes the oxidized form and NADH denotes the reduced form of nicotinamide adenine dinucleotide while NADP ⁺ denotes the oxidized form and NADPH denotes the reduced form of nicotinamide adenine dinucleotide phosphate.

As "oxidation reaction (s)" and "reduction reaction (s)" herein are meant those enzyme-catalyzed redox reactions which are not part of the cofactor regeneration and are involved in the formation of the product in a process of the present invention. and "reduction reaction (s)" are grouped together under the term "product formation reactions." The product formation reactions in a process of the present invention each include at least one

Oxidation reaction and at least one reduction reaction.

When NAD ^{+ is used} as a cofactor for the oxidation reaction (s), NADPH is the cofactor for the reduction reaction (s). Will NADP ⁺ as a cofactor for the

Oxidation reaction (s) used so is NADH the cofactor for the

Reduction reaction (s). In a process according to the present invention, oxidation reaction (s) and reduction reaction (s) can be carried out either simultaneously in time or sequentially, preferably in parallel, in the same reaction batch.

Substrates here are those compounds which are used for the purpose of product formation. Kosubstrate here are those compounds that are implemented in the cofactor regeneration.

In a method according to the invention, both a substrate and a plurality of substrates can be used. This reduction and / or

Oxidation reaction (s) both on the same substrate (molecular backbone), as well as on different substrates, preferably on the same substrate, take place. Furthermore, in a process according to the present invention reduction and / or oxidation reaction can take place on the same or on different functional groups.

A process according to the present invention is suitable for a large number of reactions, for example for configuration inversion of stereoisomeric hydroxy compounds by oxidation to the corresponding ketone and subsequent reduction to the opposite stereospecific hydroxy compound.

By "one-pot reaction" herein is meant a process wherein two or more enzymatic redox reactions involved in product formation and two enzymatic systems for cofactor regeneration occur in a reaction batch without isolating an intermediate.

The mention of an acid or the salt of an acid here includes the term not mentioned in each case. Also includes the mention of acids, in particular

Bile acids, here all esters derived therefrom. Furthermore, here (partially) compounds provided with protective groups are included in the naming of the underlying substances. In a preferred embodiment of the present invention, a process according to the present invention is characterized in that the oxidation reaction and

Reduction reaction take place in parallel in time.

In a preferred embodiment of the present invention, a process according to the present invention is characterized in that both oxidation reaction and reduction reaction take place on the same molecular backbone.

In a preferred embodiment of the present invention, a process according to the present invention is characterized in that the compound of the formula I (2-oxo acid) pyruvate (cosubstrate) is used, which is reduced by means of a lactate dehydrogenase to lactate, that is, in the regeneration reaction , which converts the reduced cofactor back into its original oxidized form by means of a

Lactate dehydrogenase pyruvate is reduced to lactate.

In a preferred embodiment of the present invention, a process according to the present invention is characterized in that as the compound of the formula II

(secondary alcohol) 2-propanol (isopropyl alcohol, IPA) (cosubstrate) is used, which is oxidized by means of an alcohol dehydrogenase to acetone, that is, in the regeneration reaction, which converts the oxidized cofactor back into its original reduced form by means of an alcohol dehydrogenase. 2 Propanol is oxidized to acetone.

In a preferred embodiment of the present invention, a method according to the invention is characterized in that oxygen is used, which is reduced by means of an NADH oxidase.

In a preferred embodiment of the present invention, a process according to the present invention is characterized in that secondary alcohol is malate

(Kosubstrat) is used, which by means of a Oxalacetat-decarboylierenden

Malatdehydro genese ("malate enzyme") is oxidized to pyruvate and C0 ₂ , for example, that in the regeneration reaction, the oxidized cofactor back to its original converted into reduced form by means of a malate dehydrogenase malate to pyruvate and C0 _{2 is} oxidized.

The resulting pyruvate is reacted in this embodiment in a further redox reaction, which does not serve for product formation, but represents the second cofactor regeneration reaction.

In a preferred embodiment of the present invention, a process according to the present invention is characterized in that it is used to carry out in each case at least one oxidation reaction and at least one reduction reaction in the same reaction mixture of compounds of the general formula

wherein

R 4 is hydrogen, a methyl group, a hydroxy group or an oxo group,

R5 is hydrogen, a hydroxy group, an oxo group or a methyl group,

R _{6 is} hydrogen or a hydroxy group,

R _{7 is} hydrogen, -COR ₁₃ , wherein R _{13 is} an unsubstituted or substituted with a hydroxy group C ₁ -C 4 alkyl group, or a substituted, in particular with a

Hydroxy group, or unsubstituted CC ₄ carboxyalkyl group,

or R ₆ and R ₇ together represent an oxo group,

R 8 is hydrogen, a methyl group, a hydroxy group or an oxo group,

R 9 is hydrogen, a methyl group, a hydroxy group or an oxo group,

Rio hydrogen, a methyl group or a halogen,

Rn is hydrogen, a methyl group, a hydroxy group, an oxo group or halogen, and

R _{12 is} hydrogen, a hydroxy group, an oxo group or a methyl group, where the structural element

a benzene ring or a ring having 6 carbon atoms and 0, 1 or 2 C-C double bonds;

wherein preferably the substrate (s) for the reduction reaction (s) involved in the product formation is / are present in a concentration of <5 (w / v) in the reaction mixture.

In a preferred embodiment of the present invention, a method according to the invention is characterized in that an enzymatic conversion of dehydroepiandrosterone (DHEA) to testosterone takes place.

In a preferred embodiment of the present invention, a process according to the invention is characterized in that an enzymatic epimerization of hydroxysteroid compound 3a, 7a-dihydroxy-5β-cholanic acid (chenodeoxycholic acid, CDC) by oxidation to ketolithocholic acid (KLC) and reduction to 3a, 7β- Dihydroxy-5β-cholanic acid (ursodeoxycholic acid, UDC) is carried out by means of two oppositely stereospecific hydroxysteroid dehydrogenases.

In a preferred embodiment of the present invention, a method according to the present invention is characterized in that a C ₅ - or C ₆ sugars used as the substrate, for example, that the process for isomerization of C ₅ - or C _ö sugars is used.

In a preferred embodiment of the present invention, a process according to the present invention is characterized in that an isomerization of glucose takes place by reduction to sorbitol and oxidation to fructose, for example that the process is used for the isomerization of glucose by reduction to sorbitol and subsequent oxidation to fructose , A process according to the invention is preferably carried out in an aqueous system, wherein it is possible that the substrate for oxidation and

Reduction reaction is partly unresolved in the form of a suspension and / or as a second liquid phase.

In a particular embodiment, a process according to the present invention is characterized in that the substrate (s) for the oxidation reaction (s) involved in the product formation are present in a concentration of at least 5% (w / v) and more, preferably 7%. (w / v) and more, more preferably 9% (w / v) and more in the

Reaction mixture is present / present.

In a particular embodiment, a process according to the present invention is characterized in that a total of> 70, in particular> 90, conversion is achieved in the product formation reactions.

In a process of the present invention, a buffer may be added to the aqueous system. Suitable buffers include, for example, potassium phosphate, tris-HCl, and glycine, having a pH of from 5 to 10, preferably from 6 to 9. Further, the system may contain ions for stabilizing the enzymes, such as Mg ²⁺ or other additives , such as glycerol are added. The concentration of added cofactors NAD (P) ⁺ and NAD (P) H in a method of the present invention is usually between 0.001 mM and 10 mM, preferably between 0.01 mM and 1 mM.

Depending on the enzymes used, the method according to the present invention

Invention at a temperature of 10 ° C to 70 ° C, preferably from 20 ° C to 45 ° C are performed.

Hydroxysteroid dehydrogenases (HSDH) are understood as meaning those enzymes which catalyze the oxidation of hydroxy groups to the corresponding keto groups or, conversely, the reduction of keto groups to the corresponding hydroxy groups on the steroid skeleton. Suitable hydroxysteroid dehydrogenases which can be used for redox reactions on hydroxysteroids are, for example, 3a-HSDH, 3β-HSDH, 7a-HSDH, 7β-HSDH or 17β-HSDH.

Suitable enzymes having 7a-HSDH activity are obtainable, for example, from clostridia (Clostridium absonum, Clostridium sordelii), Escherichia coli or Bacteroides fragilis.

Suitable enzymes having 7β-HSDH activity are available, for example, from Ruminococcus sp. or Clostridium absonum.

Suitable lactate dehydrogenases are available, for example, from Oryctolagus cuniculus. Suitable alcohol dehydrogenases are obtainable, for example, from Lactobacillus kefir.

For example, a suitable xylose reductase is available from Candida tropicalis.

Suitable sorbitol dehydrogenases are for example obtainable from sheep liver, Bacillus subtilis or Malus domestica.

Suitable NADH oxidases are available, for example, from Leuconostoc mesenteroides, Streptococcus mutans, Clostridium aminovalericum.

In a method according to the invention, enzymes are preferably used as proteins overexpressed recombinantly in E. coli, furthermore preferably the

appropriate cell lysates are used without further purification. The enzyme unit 1 U corresponds to that amount of enzyme that is needed to implement 1 μιηοΐ substrate per min.

Description of the pictures Fig. 1 shows the reaction scheme of the epimerization of chenodeoxycholic acid

Ursodeoxycholic acid via the intermediate 3a-hydroxy-7oxo-5β-cholanic acid with cofactor regeneration using 2-propanol and pyruvate.

Fig. 2 shows the reaction scheme of the epimerization of chenodeoxycholic acid

Ursodeoxycholic acid via the intermediate 3a-hydroxy-7oxo-5β-cholanic acid with cofactor regeneration using malate and pyruvate.

Fig. 3 shows the reaction scheme of the epimerization of chenodeoxycholic acid

Ursodeoxycholic acid via the intermediate 3a-hydroxy-7oxo-5β-cholanic acid with cofactor regeneration using 2-propanol and oxygen.

Figure 4 shows the reaction scheme of isomerization of glucose to fructose with cofactor regeneration using 2-propanol and pyruvate.

Figure 5 shows the reaction scheme of isomerization of glucose to fructose with cofactor regeneration using 2-propanol and oxygen.

In the illustrations, the following abbreviations are used:

BsSDH sorbitol dehydrogenase from Bacillus subtilis

Caoxo clostridium aminovalericum NADH oxidase

CDC 3a, 7a-dihydroxy-5β-cholanic acid

CtXR Candida tropicalis xylose reductase

7a-HSDH 7a hydroxysteroid dehydrogenase

7β-HSDH 7β-hydroxysteroid dehydrogenase

KLC 3a-hydroxy-7-oxo-5β-cholanic acid

LacDH lactate dehydrogenase NAD (H) -dependent

LkADH Lactobacillus kefir alcohol dehydrogenase NADP (H) -dependent:

MalDH E. coli malate dehydrogenase NADP (H) -dependent

SISDH sheep liver sorbitol dehydrogenase

SmOxo Streptococcus mutans NADH oxidase

UDC 3a, 7β-Dihydroxy-5β-cholanic acid In the examples below, all Tempreatur data are in degrees Celsius (° C). The following abbreviations are used:

EtOAc ethyl acetate

h hour (s)

IPA isopropyl alcohol (2-propanol)

MeOH methanol

Rt room temperature

example 1

Epimerization of chenodeoxycholic acid to ursodeoxycholic acid by 7α-hydroxysteroid dehydrogenase and 7β-hydroxysteroid dehydrogenase using a lactate dehydrogenase and alcohol dehydrogenase-dependent cofactor regeneration system

A 0.5 ml mixture contains 50 mg chenodeoxycholic acid, 12 U of recombinant 7α-hydroxysteroid dehydrogenase from Escherichia coli, 6 U of recombinant 7β-hydroxysteroid dehydrogenase from Ruminococcus torques, and 0.5 mM NAD ⁺ and 0.3 mM NADPH. For the regeneration of NAD ⁺ 6 U recombinant lactate dehydrogenase and 350 mM sodium pyruvate are used. For the regeneration of NADPH, 6 U of the recombinant alcohol dehydrogenase from Lactobacillus kefir and initially 2.4% IPA (w / v) are used. The reaction is carried out in an aqueous potassium phosphate buffer (100 mM, pH = 7.8) at 25 ° C and with continuous shaking (850 rpm). An open system is also used to allow the evaporation of acetone and to shift the reaction towards ursodeoxycholic acid. There are 1.6% (w / v) IPA after 6 h, 2.4% (w / v) IPA after 16 h, 3.9% (w / v) IPA after 24 h and 0.8% (w / v) IPA dosed in after 40 h. In addition, 20 μΐ 4-methyl-2-pentanol are added after 24 h. After 46 hours, 200 μM 2-pentanol and 1.6% (w / v) IPA are added. After 48 h, the proportion of ursodeoxycholic acid in all bile acids in the reaction mixture is> 97%.

Example 2

Epimerization of chenodeoxycholic acid to ursodeoxycholic acid by 7α-hydroxysteroid dehydrogenase and 7β-hydroxysteroid dehydrogenase using a lactate dehydrogenase and malate dehydrogenase-dependent cofactor regeneration system

A 0.5 ml mixture contains 50 mg chenodeoxycholic acid, 20 U of the recombinant 7α-hydroxysteroid dehydrogenase from Escherichia coli, 20 U of the recombinant 7β-hydroxysteroid dehydrogenase from Ruminococcus torques and 1 mM NAD ⁺ and 1 mM NADPH.

For the regeneration of NAD ⁺ 10 U of lactate dehydrogenase (Sigma-Aldrich) and 16.5 mM sodium pyruvate are used to start the reaction. For the regeneration of NADPH, 20 U of the recombinant malate dehydrogenase from Escherichia coli and 320 mM sodium malate used. The reaction is carried out in an aqueous potassium phosphate buffer (100 mM, pH = 7.8) at 25 ° C and with continuous shaking (850 rpm). An open system is also used to allow escape of the resulting C0 ₂ . 20 U 7a-HSDH and 10 U lactate dehydrogenase were dosed in after 16 h and 40 h. 10 7β-HSDH were dosed in after 20 h, 24 h, 44 h and 48 h.

Furthermore, 10 U Malatdehydro genese were post-dosed after 40 h. After 72 h, the proportion of ursodeoxycholic acid in all bile acids in the reaction mixture is about 90%.

Example 3

Epimerization of chenodeoxycholic acid to ursodeoxycholic acid by 7α-hydroxysteroid dehydrogenase and 7β-hydroxysteroid dehydrogenase using an NADH oxidase and alcohol dehydrogenase-dependent cofactor regeneration system

A 0.5 ml mixture contains 50 mg chenodeoxycholic acid, 12 U of the recombinant 7α-hydroxysteroid dehydrogenase from Escherichia coli, 7.5 U of the recombinant 7β-hydroxysteroid dehydrogenase from Ruminococcus torques and 1 mM NAD ⁺ and 1 mM NADPH. For the regeneration of NAD ⁺ , 20 U of the recombinant NADH oxidase from Clostridium aminovalericum are used. For the regeneration of NADPH 5 U of the recombinant alcohol dehydrogenase from Lactobacillus kefir and initially 2% IPA (w / v) are used. The reaction is carried out in an aqueous potassium phosphate buffer (100 mM, pH 6) at 25 ° C with continuous shaking (850 rpm). An open system is also used to allow the evaporation of acetone and to shift the reaction towards ursodeoxycholic acid. 2% IPA are dosed after 18 h, 22 h, 26 h and 41 h and 5% IPA after 41 h and 48 h. After 24 h, 20 U of NADH oxidase and after 41 h of 7.5 U of 7ß-hydroxysteroid dehydrogenase and 5 U alcohol dehydrogenase are replenished. After 48 h, the proportion of ursodeoxycholic acid in all bile acids in the reaction mixture is about 95-98%.

Example 4

Work-up and analysis of bile acids

After completion of reactions as described in Examples 1 to 3, the reaction mixture is extracted with EtOAc. The solvent is then by means of Evaporation removed. The conversion of chenodeoxycholic acid to ursodeoxycholic acid is monitored by dissolution in a mixture of MeOH: acetonitrile: sodium phosphate buffer pH = 3, 0.78 g / l (40:30:37), by HPLC. Here, a reversed-phase column (ZORBAX Eclipse ^® ^® XDB C18, flow 0.8 ml / min) and a refraction detector (RID), Agilent 1260 Infinity ^®, both used by Agilent Technologies Inc.,.

Example 5

The conversion of glucose to fructose by a xylose reductase and a

Sorbitol dehydrogenase using an alcohol dehydrogenase to recycle the NADPH and a lactate dehydrogenase to recycle the NAD ⁺

A 0.5 ml batch contains 50 mg / ml glucose and 6 U / ml of the recombinant xylose reductase from Candida tropicalis and 0.1 mM NADP ⁺ . To regenerate the cofactor, 7% IPA and the recombinant alcohol dehydrogenase from Lactobacillus kefir are added. The enzymes are used in the form of cell lysate. The reaction takes place for 24 h at 40 ° C and pH = 9 with continuous shaking (900 rpm) in an open system. The open system leads to the removal of the acetone, which drives the reaction towards sorbitol formation. In the open system water and IPA also evaporate, so that they are dosed after 6 h and 21 h. After 24 hours, the reaction vessel is incubated at 60 ° C under vacuum to deactivate the enzymes and to evaporate the organic solvents. After cooling to Rt, the recombinant sorbitol dehydrogenase from Bacillus subtilis is added at a final concentration of 5 U / ml, ZnCl ₂ in a final concentration of 1 mM and NAD ⁺ in a final concentration of 0.1 mM. For cofactor regeneration, 5 U / ml (final concentration) of lactate dehydrogenase

Rabbit muscle and 300 mM pyruvate used. The batch is made up to 0.5 ml with water. The reaction takes place for 24 h at 40 ° C and pH = 9 under continuous

Shaking (900 rpm) in the closed system instead. It is achieved a turnover of> 90.

Example 6

Conversion of glucose to fructose by a xylose reductase and a sorbitol dehydrogenase using an alcohol dehydrogenase to recycle the NADPH and an oxidase to recycle the NAD ⁺ A 0.5 ml batch contains 50 mg / ml glucose, 6 U / ml of the recombinant xylose reductase from Candida tropicalis and 0.1 mM NADP ⁺ . To regenerate the cofactor, 7% IPA and the recombinant alcohol dehydrogenase from Lactobacillus kefir are added. The enzymes are used in the form of cell lysate. The reaction takes place for 24 h at 40 ° C and pH = 8 with continuous shaking (900 rpm) in an open system. The open system leads to the removal of the acetone, which drives the reaction towards sorbitol formation. In the open system water and IPA also evaporate, so that they are dosed after 6 h and 21 h. After 24 h, the reaction vessel is incubated at 60 ° C under vacuum to deactivate the enzymes and to evaporate IPA, as well as resulting acetone. After cooling to room temperature, the recombinant

Sorbitol dehydrogenase from Bacillus subtilis at a final concentration of 5 U / ml, CaCl ₂ at a final concentration of 1 mM and a mixture of NAD ⁺ and NADH added in a final concentration of 0.1 mM. For cofactor regeneration 10 U / ml (final concentration) of the oxidase from Leuconostoc mesenteroides are used. The batch is made up to 0.5 ml with water. The enzymes are used in the form of cell lysate. The reaction takes place for 24 h at 40 ° C and pH = 8 with continuous shaking (900 rpm) in the open system to ensure enough oxygen to supply the oxidase from the air. In the open system at 40 ° C water evaporates, which must be post-dosed after 6 h and 21 h. A conversion of glucose to fructose of> 98 is achieved.

Example 7

Processing and analysis of sugars

The batch is incubated for 10 min at 65 ° C to deactivate the enzymes and then centrifuged. The supernatant is then filtered through a 0.2 μΜ PVDF filter and analyzed by Ligand Exchange HPLC (Agilent Technologies Inc.). Be separated sugars and polyols here via a lead column by Showa Denko KK (Shodex Sugar ^® SP0810) / with a flow of 0.5 ml min water (VWR International Ltd., HPLC grade) at 80 ° C. The detection is performed by means of refraction of light detector (RID, Agilent 1260 Infinity ^®, Agilent Technologies Inc.). There is an in-line filter by Agilent Technologies Inc., as well as pre-columns, a anion exchange column (Shodex ^® Axpak-WAG), a reversed-phase column (Shodex Asahipak ^® ^® ODP-50 6E) and a sugar precolumn

(SUGAR SP-G) by Showa Denko K.K. used.

Claims

claims

1. A process for the enzymatic regeneration of the redox cofactors NAD ⁺ / NADH and NADP ⁺ / NADPH in a one-pot reaction, wherein as a result of at least two further running in the same reaction mixture enzymatically catalyzed

Redox reactions (product formation reactions) of one of the two redox cofactors obtained in its reduced form and the other in its oxidized form, characterized in that

a) in the regeneration reaction, the reduced cofactor back in his

original oxidized form, oxygen or a compound of general formula

wherein R is a straight-chain or branched-chain (C ₁ -C ₄ ) -alkyl group or a (C ₁ -C ₄ ) -carboxyalkyl group, is reduced, and

b) in the regeneration reaction, the oxidized cofactor in his

converted original reduced form, a (C ₄ -Cg) cycloalkanol or a

Compound of the general formula

wherein R ₂ and R _{3 are} independently selected from the group consisting of H, (C ₁ -C _ö) -alkyl, wherein alkyl is straight chain or branched (C ₁ -C _ö) -alkenyl, wherein alkenyl is straight-chain or branched and one to three double bonds, aryl, in particular C ₆ -C ₁₂ aryl, carboxyl, or (C ₁ -C ₄ ) -carboxyalkyl, in particular also cycloalkyl, for example C ₃ -C 8 -cycloalkyl,

is oxidized.

2. The method of claim 1 for the enzymatic regeneration of the redox cofactors NAD ⁺ / NADH and NADP ⁺ / NADPH in a one-pot reaction, with as a result at least two further enzymatically catalyzed redox reactions (= product formation reactions) taking place in the same reaction mixture of one of the two

Redox cofactors accumulates in its reduced form and the other in its oxidized form, characterized in that

wherein Ri is a substituted or unsubstituted C 1 -C 4 -alkyl group, and b) in the regeneration of the reduced cofactor, a compound of the general formula II is oxidized,

1) -H),

2) - (C 1 -C 6) -alkyl, in which alkyl is straight-chain or branched-chain,

3) - (Ci-Cö) - alkenyl, wherein alkenyl is straight or branched chain and

optionally contains up to three double bonds,

4) -cycloalkyl, in particular C ₃ -C 8 -cycloalkyl,

5) -aryl, in particular C ₆ -C ₁₂ aryl,

6) - (C ₁ -C ₄ ) carboxyalkyl, if compound I is pyruvate,

optionally also carboxyl.

3. The method according to any one of claims 1 or 2, wherein R ₂ and R independently

are selected from the group consisting of H, (C -C) - alkyl, wherein alkyl is straight or branched, (C Cö) - alkenyl, wherein alkenyl is straight or branched and contains one to three double bonds, aryl, in particular C ₆ -C ₁₂ aryl, carboxyl or (C ₁ -C ₄ ) carboxyalkyl.

4. The method according to any one of claims 1 to 3, characterized in that

Oxidation reaction (s) and reduction reaction (s) on the same substrate

(Molecular framework) take place.

5. The method according to any one of claims 1 to 4, characterized in that

Oxidation reaction (s) and reduction reaction (s) run parallel in time.

6. The method according to any one of claims 1 to 5, characterized in that in the regeneration reaction, which converts the oxidized cofactor back into its original reduced form by means of an alcohol dehydrogenase 2-propanol is oxidized to acetone.

7. The method according to any one of claims 1 to 5, characterized in that in the regeneration reaction, which converts the reduced cofactor back into its original oxidized form by means of a lactate dehydrogenase pyruvate is reduced to lactate.

8. The method according to claim 7, characterized in that in the

Regeneration reaction, which converts the oxidized cofactor back to its original reduced form by means of a malate dehydrogenase malate to pyruvate and C0 _{2 is} oxidized.

9. The method according to any one of claims 1 to 7, characterized in that it is used for carrying out in each case at least one oxidation reaction and at least one reduction reaction in the same reaction mixture of compounds of the general formula

wherein

R _{4 is} hydrogen, a methyl group, a hydroxy group or an oxo group, R _{5 is} hydrogen, a hydroxy group, an oxo group or a methyl group, R _{6 is} hydrogen or a hydroxy group,

R _{7 is} hydrogen, -COR ₁₃ , in which R _{13 is} an unsubstituted or hydroxy-substituted C ₁ -C 4 -alkyl group, or a substituted, especially with a hydroxy group, or unsubstituted C _4- carboxyalkyl group,

or R ₆ and R ₇ together represent an oxo group,

R 8 is hydrogen, a methyl group, a hydroxy group or an oxo group, R 9 is hydrogen, a methyl group, a hydroxy group or an oxo group, R 10 is hydrogen, a methyl group or halogen,

Rn is hydrogen, a methyl group, a hydroxy group, an oxo group or halogen, and

R _{12 is} hydrogen, a hydroxy group, an oxo group or a methyl group,

wherein the structural element

a benzene ring or a ring having 6 carbon atoms and 0, 1 or 2 C-C double bonds; in particular wherein the substrate (s) for the reduction reaction (s) involved in the product formation are present in a concentration of <5 (w / v) in the reaction mixture.

10. The method according to claim 9, characterized in that it is used for the conversion of dehydroepiandrosterone (DHEA) of the formula

in testosterone of the formula

11. The method according to claim 9, characterized in that it is used for

enzymatic epimerization of 3a, 7a-dihydroxy-5β-cholanic acid

(Chenodeox

by oxidation to ketolithocholic acid of the formula

and subsequent reduction to the stereoisomeric hydroxy compound 3, 7β-dihydroxy-5β-cholanic acid (ursodeoxycholic acid) of the formula

by means of two opposite stereospecific hydroxysteroid dehydrogenases.

12. The method according to claim 11, characterized in that the oxidation reaction is catalyzed by a 7-hydroxysteroid dehydrogenase from E. coli.

13. The method according to claim 11, characterized in that the reduction reaction

catalyzed by a 7ß-hydroxysteroid dehydrogenase from Ruminococcus torques.

14. The method according to any one of claims 1 to 8, characterized in that it is used for the isomerization of C ₅ - or C _ö sugars.

15. The method according to claim 14, characterized in that it is used for

Isomerization of glucose by reduction to sorbitol and subsequent oxidation to fructose.

16. The method according to any one of claims 1 to 15, characterized in that the

Substrate (s) for the oxidation reaction (s) involved in product formation in a concentration of 5% (w / v) and more, in particular 7% (w / v) and more, in particular 9% (w / v) v) and more present / present in the reaction mixture.

17. The method according to any one of claims 1 to 16, characterized in that in the product formation reactions in total a conversion of> 70, in particular> 90 is achieved.