CN105274082B

CN105274082B - A kind of synthesis penicillin G acylase mutant and its application in preparing Amoxicillin

Info

Publication number: CN105274082B
Application number: CN201510736957.7A
Authority: CN
Inventors: 许岗; 黄斌; 郭宁; 周晶辉; 赵强; 曾红宇
Original assignee: Hu'nan Fulaige Biological Technology Co Ltd
Current assignee: Hu'nan Fulaige Biological Technology Co Ltd
Priority date: 2015-11-03
Filing date: 2015-11-03
Publication date: 2018-08-31
Anticipated expiration: 2035-11-03
Also published as: CN105274082A

Abstract

The present invention provides a kind of synthesis penicillin G acylase mutant and its applications in preparing Amoxicillin.Half design and rational of fixed point saturation mutation technology and the enzyme engineering renovation technique of orthogenesis is combined to be mutated the penicillin G acylase in Achromobacter xylosoxidans source by CAD; it is lower to obtain hydrolysis vigor; synthesis of dynamic is more preferable; synthesize that hydrolysis ratio (S/H) higher, acid resistance be stronger and the better penicillin G acylase mutant of stability; can be more effective, rapidly catalyze and synthesize Amoxicillin.The 4 immobilized enzyme hydrolysis vigor of mutant SPGA that the present invention obtains has dropped 8.7 times, synthesis of dynamic improves 5.6 times, S/H values improve 8 times, 60min keeps 79% vigor under the conditions of pH2.0, catalyzes and synthesizes Amoxicillin using 10 DEG C or 20 DEG C of solid process, the wherein 6 direct solids of APA and D HPM of substrate feed intake without dissolving, pH is reacted without control, 300 batches or more can be used continuously 99% or more in substrate conversion efficiency, have good operational stability.

Description

A kind of synthesis penicillin G acylase mutant and its in preparing Amoxicillin Using

Technical field

The invention belongs to genetic engineering and enzyme engineering field, it is prominent that particular content is related to a kind of synthesis penicillin G acylase The application of variant and the mutant immobilised enzymes in preparing Amoxicillin production.

Background technology

Amoxicillin (Amoxicillin) is a kind of most common penicillins wide spectrum beta-lactam antibiotic.Mesh Before, the industrial method for producing Amoxicillin has two methods of chemical synthesis and enzyme process, and enzyme process is relatively low with cost, technique is simple Singly, the advantages that green non-pollution and reaction condition are mild, therefore, is paid more and more attention.

Penicillin G acylase (penicillin G acylase, PGA, EC 3.5.1.11), is catalyzed in acid condition Parent nucleus (6-APA or 7-ADCA) and side chain synthesis beta-lactam antibiotic are (such as：Amoxicillin, ampicillin, cefalexin With cefadroxil etc.)；Hydrolyzing penicillin G prepares 6-APA under alkaline condition or hydrolysis Cephalosporin G prepares 7-ADCA.

The source of the penicillin G acylase of wild type is very extensive, is acylated currently, having filtered out numerous production benzyl penicillins The microorganism of enzyme simultaneously by its encoding gene clone come, as escherichia coli (Escherichia coli ATCC 11105), Flavobacterium (Flavobacterium sp.650), bacillus megaterium (Bacillus megaterium), Bacillus foecalis alkaligenes (Alcaligenes faecalis), Achromobacter xylosoxidans (Achromobacter xylosoxidans), achromobacter Belong to (Achromobacter sp.CCM 4824), thermophilic grams of citric acid Lv Woer Salmonellas (Kluyvera citrophila), Lei Shi Providence (Providencia rettgeri) etc..

Currently, being found during Production by Enzymes Amoxicillin, wild type Penicillin G acylases hydrolysing activity is high, closes The shortcomings of Viability low, synthesis hydrolysis is smaller than (S/H), side chain consumption is high, the acid resistance of especially enzyme is weak, stability is poor, cause The cost that enzyme process prepares Amoxicillin is higher.

With the development of genetic engineering and protein engineering techniques, domestic and international researcher is with design and rational, half rationality The report that the means such as design and nonideal explosives carry out mutation transformation to the synthesis performance of penicillin G acylase has very much, such as In Chinese patent CN101177688, Huang He, huge rock etc. are with homologous modeling and site-directed mutagenesis technique to bacillus megaterium PGA 144 sites α on tyrosine sport 24 site of arginine and β valine mutation be phenylalanine, obtain mutant Synthesis performance, S/H ratios and the 7-ADCA conversion ratios of enzyme all improve a lot；In Chinese patent CN 103275960, Lai Hong Star, Xiao Yongjun etc. to achromobacter penicillin G acylase proenzyme engineer and express, obtain one kind can synthesize Ah The PGA of Amdinocillin, enzyme activity have reached 28000U/L (composing type) or 35000U/L (induction type)；Cheng Tianfan (Zhejiang University Master thesis, 2005) the mixed group of DNA families is carried out in combination with inhibition zone screening technique to 5 kinds of wild type PGA genes, it obtains Obtained synthesis performance and PGA mutant that S/H values all significantly improve；Senwen Deng, Erzheng Su etc. (Journal of Biotechnology,Volume 199, 10April 2015, Pages 62-68) and utilize albumen renovation technique to produce alkali bar to excrement Bacterium PGA is transformed, and the phenylalanine on its 24 site β is sported glycine, alanine, serine or proline, wherein F The effect of β 24G synthesis ampicillin is best；International patent application WO2010/072765 is reported to E.coli ATCC 11105 The PGA in source is transformed, and is carried out to its A3, A77, A90, A144, A192, B24, B109, B148, B313, B460 and B488 Single-point or combinatorial mutagenesis obtain synthesis performance and multiple mutant that S/H values greatly improve；European patent EP 0961825 is reported With protein engineering techniques alanine or leucine are sported to the phenylalanine on 24 sites β of Escherichia coli PGA, closed It is greatly promoted at the ability of ampicillin and cefalexin.

Although being transformed both at home and abroad to penicillin G acylase using genetic engineering and protein engineering techniques, make its synthesis Performance and synthesis of dynamic are greatly improved, and still, the acid resistance of mutant enzyme is also very weak, synthesizing activity is also relatively low and fixes Changing the operational stability of enzyme also needs to further increase.Therefore, develop that a kind of acid resistance is strong, synthesizing activity is high and operational stability is good Enzyme be of great significance.

Invention content

That the first purpose of the invention is to provide a kind of acid resistances is strong, hydrolysing activity is low, synthesizing activity is high, S/H values are high and The good penicillin G acylase mutant of operational stability.It is in Achromobacter xylosoxidans (Achromobacter Xylosoxidans) there is a point mutation in site following six on the basis of wild type Penicillin G acylations enzyme amino acid sequence Or multi-point combination mutation：The 162nd amino acids sport the 24th amino acids on L, β subunit by M and sport G, β by F on α subunits The 241st amino acids sport the 71st amino acids on Q, β subunit by N and sport the 64th bit amino on Y, β subunit by F on subunit Acid sports the 310th amino acids on T, β subunit by A and sports V by A；

Described Achromobacter xylosoxidans (Achromobacter xylosoxidans) the wild type Penicillin G acylases The intermediate connection peptide and 557 amino acid groups that α subunits that amino acid sequence is made of 232 amino acid, 54 amino acid form At β subunit three parts constitute, sequence is as shown in SEQ ID NO.1.

Gradually preferred sequence is as follows for the penicillin G acylase mutant：

1, it is to have following four sites on the basis of the wild type Penicillin G of SEQ ID NO.1 is acylated enzyme amino acid sequence In a point mutation or multi-point combination mutation：The 162nd amino acids sport the 24th bit amino on L, β subunit by M on α subunits Acid by F sports the 241st amino acids on G, β subunit and sports the 71st amino acids on Q, β subunit by N sports Y by F.

2, it is on the basis of the wild type Penicillin G of SEQ ID NO.1 is acylated enzyme amino acid sequence to the on β subunits the 241st Amino acids sport Q, as SPGA-1 mutant by N.

3, it is on the basis of the amino acid sequence of SPGA-1 just like next point mutation or two point mutation or three point groups Close mutation：The 162nd amino acids sport the 24th amino acids on L, β subunit by M and are sported on G, β subunit by F on α subunits 71 amino acids sport Y by F, wherein it is preferred that on the basis of the amino acid sequence of SPGA-1 carry out three combinatorial mutagenesis, obtain 4 combination mutant SPGA-2 of enzyme amino acid sequence are acylated to wild type Penicillin G.

4, it is that T is sported by A to the 64th amino acids on β subunits on the basis of the amino acid sequence of SPGA-2, the mutation Body is SPGA-3A mutant.Either on the basis of the amino acid sequence of SPGA-2 to the 310th amino acids on β subunits by A V is sported, which is SPGA-3B mutant.

5, it is most preferably that T is sported by A to the 64th amino acids on β subunits on the basis of the amino acid sequence of SPGA-2, V is sported to the 310th amino acids on β subunits by A to obtain wild type Penicillin G and be acylated 6 points of enzyme amino acid sequence and combine to dash forward Variant, as SPGA-4, sequence such as SEQ ID NO:Shown in 3.

Second object of the present invention is to provide the nucleotide sequence of above-mentioned penicillin G acylase mutant, is following It is any：

1) nucleotide sequence of any one of above-mentioned penicillin G acylase mutant；

Any one of 1) 2) there is penicillin G acylase with the nucleotide sequence hybridization and coding limited under strict conditions The nucleotide sequence of active protein；

Any one of 1) or 2) 3) there is 90% or more homology with the gene order limited and encodes with benzyl penicillin The nucleotide sequence of the protein of acylase activity.

The preparation method of the mutant penicillin G acylases of the present invention, includes the following steps：

A) by the Achromobacter xylosoxidans (Achromobacter with SEQ ID NO.2 in sequence table Xylosoxidans) wild type Penicillin G acylases carry out saturation mutation, iteration saturation mutation and random mutation and etc. obtain Encode the gene order of the mutant of any of the above-described kind of penicillin G acylase；

B) mutant gene sequence is inserted into plasmid and obtains expression vector；

C) expression vector conversion is entered in bacterial strain and obtains recombination engineering bacteria；

D) recombination engineering bacteria is induced with lactose and is fermented to obtain penicillin G acylase.

The preparation method of mutant penicillin G acylases of the present invention further includes further purification step, pure Change step be will produce penicillin G acylase recombinant bacterium broken, centrifugation, collect after by immobilization metal chelating affinity chromatography into Row purifying obtains the pure enzyme of penicillin G acylase.

Further, further include enzyme immobilizatio step, immobilization step is that above-mentioned enzyme solution after purification is used phosphate Buffer solution (pH 8.0,0.1mol/L) dissolves, and activated treated the carriers of 50g is then added, under the conditions of 25 DEG C, 120rpm Stirring at low speed immobilization 48h, gained immobilised enzymes is cleaned 3~5 times repeatedly with deionized water, immobilization to obtain the final product after vacuum is filtered dry Enzyme finished product.

Further, fixation support is epoxy base carrier ECEP or amino carrier ECHA/S.

Further, plasmid is pET28b (+), and bacterial strain is E.coli BL21 (DE3).

Third object of the present invention is to provide the mutant immobilised enzymes of above-mentioned penicillin G acylase to prepare Ah not Application in XiLin.

The application is specially：Using the penicillin G acylase mutant immobilised enzymes of the present invention as catalyst, using 10 DEG C or 20 DEG C of solid process catalyze and synthesize Amoxicillin, wherein the direct solids of substrate 6-APA and D-HPM feed intake without dissolving, process In reaction controlling, reaction pH is without control, it is only necessary to 10 DEG C or 20 DEG C of controlling reaction temperature.

Advantage of the present invention：

The present invention combines half design and rational and orthogenesis for pinpointing saturation mutation technology by CAD Enzyme engineering renovation technique is acylated the benzyl penicillin in the source Achromobacter xylosoxidans (Achromobacterxylosoxidans) Enzyme is mutated, and obtains that hydrolysis vigor is lower, and synthesis of dynamic is more preferable, synthesis hydrolysis ratio (S/H) higher, acid resistance it is stronger and The better penicillin G acylase mutant of stability, can be more effective, rapidly catalyzes and synthesizes Amoxicillin.

Other than objects, features and advantages described above, the present invention also has other objects, features and advantages. Below with reference to accompanying drawings, the present invention is described in further detail.

Description of the drawings

The attached drawing constituted part of this application is used to provide further understanding of the present invention, schematic reality of the invention Example and its explanation are applied for explaining the present invention, is not constituted improper limitations of the present invention.In the accompanying drawings：

Fig. 1 is that the SPGA in the embodiment of the present invention catalyzes and synthesizes Amoxicillin schematic diagram；

Fig. 2 is the SPGA protein three-dimensional structure figures in the embodiment of the present invention；

Fig. 3 is SPGA-Amoxicillin complex structure figures in the embodiment of the present invention；

Fig. 4 is the SDS-PAGE collection of illustrative plates of the preferred embodiment of the present invention；

Fig. 5 is the HPLC figures that SPGA in the embodiment of the present invention 4 catalyzes and synthesizes Amoxicillin, specially mutant SPGA-4 The HPLC figures of immobilized enzyme catalysis 6-APA and D-HPM synthesis Amoxicillin.

Specific implementation mode

Embodiment

1, the method used in following embodiments is conventional method unless otherwise specified, such as《Molecular Cloning: A Laboratory refers to South》(J. Pehanorm Brookers, D.W. Russells write, and Huang Peitang, Wang Jiaxi, Zhu Houchu are waited and translated.3rd edition, Beijing：Scientific publication Society, 2002) method described in carries out.Mutant primer and sequence are the limited public affairs of calm and peaceful Yongchang (Changsha) biotechnology Department completes.E. coli host bacteria is that E.coli BL21 (DE3) are purchased from Merck companies, and e. coli host bacteria can also be E.coli BL21 (DE3) plys, is purchased from Tiangeng company, and prokaryotic expression carrier pET28b (+) is purchased from Merck companies.DNA inscribes Enzyme Dpn I are purchased from Fermentas companies.Autopotentiometric titrator is purchased from Wan Tong companies of Switzerland, and 8 series of model is purchased from Mei Te Le-support benefit company, remaining material is commercially available.Meanwhile the amino acid in the present invention without illustrate it is outer with its abbreviation or Code name is indicated (amino acid Chinese and English title and its abbreviation and code name are shown in Table 1).

1 amino acid Chinese and English title of table and its abbreviation and code name

Chinese

English name

Abbreviation

Code name

Chinese

English name

Abbreviation

Code name

Alanine

Ala

A

Proline

Pro

P

Arginine

Arg

R

Leucine

Leu

L

Asparagine

Asn

N

Isoleucine

Ile

I

Aspartic acid

Asp

D

Glycine

Gly

G

Cysteine

Cys

C

Phenylalanine

Phe

F

Glutamine

Gln

Q

Methionine

Met

M

Glutamic acid

Glutamicacid

Glu

E

Lysine

Lys

K

Threonine

Thr

T

Histidine

His

H

Tryptophan

Trp

W

Valine

Val

V

Serine

Ser

S

Tyrosine

Tyr

Y

The mutant penicillin G acyls that hydrolysing activity is low in order to obtain, synthesizing activity is high, acid resistance is strong and operational stability is good Change enzyme, the wild type Penicillin G acylases that the present invention uses are derived from Achromobacter xylosoxidans (Achromobacterxylosoxidans), according to Cai Gang, (doctoral thesis, Shanghai Inst. of Life Science, CAS are planted Object physiological ecological research institute) with acid tolerance well, (pH5.0 keeps 85% work to research discovery wild type PGA Power), there is good thermal stability (60 DEG C keep stablize) and preferable synthesis performance, while wild type PGA encoding genes Sequence by successful clone to pET28b (+) prokaryotic expression carrier and be transferred to E.coli BL21 (DE3) formed recombinant expression Genetic engineering bacterium (the present inventor is named as SPGA-WT), the recombination engineering bacteria is by Chinese Academy of Sciences's Shanghai school of life and health sciences Friendship is given.

The amino acid sequence and nucleotide sequence of Achromobacter xylosoxidans wild type Penicillin G acylases are shown in SEQ ID NO：1 and SEQ ID NO：2.

Achromobacter xylosoxidans wild type Penicillin G is acylated enzyme amino acid sequence explanation：

MAQPVAQAAGQESAAVAAPAQGAAGKVTIRRDAHGMPHVYADTVYGIFYGYGYAVAQDRLFQMEMARRSTQGRVAEV LGASMVAFDKSIRGNFSPERIQRQLAALPAADRQVLDGYAAGMNAWLARIRAQPGQLMPKEFNDLGFAPADWTAYDV AMIFIGTMANRFSDANSEIDNLALLTALKDRHGEAEAMRIFNQLRWLTDSRAPTTVPPQEGSYQPAVFQPEGAEQLA Y SNMWIVGRDHAKDARSILLNGPQFGWWNPAYTYGIGLHGAGFDVVGNTPFAYPSILFGHNAHVAWGSTAGFGDDVDI YAEKLDPADRNRYFHDGQWKTLEKRTDLILVKDAAPVTLDVYRSVHGLIVKFDDAQHVAYAKARAWEGFELQSLMAW TRKTQSANWEQWKTQAARHALTINWYYADDRGNIGYAHTGFYPRRRPGHDPRLPVPGTGEMDWLGLLPFSTNPQVYN PGQGFIANWNNQPMRGYPSTDLFAIVWGQADRYAEIETRLKAMTANGGKVSPQQMWDLIRTTSYADVNRRHFLPFLQ RAVQGLPADDPRVRLVAGLGGWDGMMTSEREPGYYDNAGPAVMDAWLRAMLKRTLADEMPADFFKWYSATGYPTPQA PATGSLNLTTGVKVLFNALAGPAAGVPQRYDFFNGARADDVILAALDDALAALRQAYGKDPAAWKIPAPPMVFAPKN FLGVPQADAKAVLSYPATQNRGTENNMTVFDGKSVRAVDVVAPGQSGFVAPDGTPSPHTRDQFDLYNSFGSKRVWFT ADEVRRNATSEETLRYRR

The complete polypeptide chain of the gene code is by α subunits (232 amino acid), intermediate connection peptide (54 amino Acid --- overstriking underscore part) and β subunits (557 amino acid) three parts composition.Centre connection peptide adds after protein translation It is automatically removed between duration, obtains the penicillin G acylase with enzymatic activity being made of α subunits and β subunits.In α subunits Middle amino acid is numbered as A1-A232, and amino acid is numbered as B1 to B557 in β subunits.

2, the detection of penicillin G acylase enzyme activity and S/H values

(1) penicillin G acylase hydrolysis vigour-testing method (titration)

Principle：Benzyl penicillin is converted to 6-APA and phenylacetic acid under penicillin G acylase effect, in NaOH solution and benzene Acetic acid calculates penicillin G acylase vigor according to the consumption of NaOH.

Concrete operation method：It is previously added bead in 1.5ml centrifuge tubes, when bead reaches centrifuge tube scale Stop at 1.0ml, the penicillin G acylase in accurate measuring 0.5ml Examples 1 to 4 is in frequency of oscillation in centrifuge tube After vibrating 10min on the MS3 oscillators of 1500/min, by sample together with bead (immobilised enzymes 0.05g), add to In the reactor of the 1% potassium penicillin G substrate solution equipped with the 30ml for being preheated to 25 DEG C, 25 DEG C of constant temperature water bath is adjusted, is used Start timing when the sodium hydroxide titration liquid tune pH to 8.00 of 0.1mol/L, it is that 8.00 condition is stirred to react 5 minutes to keep pH, The consumption of sodium hydroxide titration liquid is detected with autopotentiometric titrator.

Enzyme activity unit (U) is defined as：At 25 DEG C, under the conditions of pH8.0,1 μ of substrate benzyl penicillin generation is catalyzed in 1min Required enzyme amount is 1U when mol phenylacetic acids.

(2) penicillin G acylase synthesis of dynamic assay method (HPLC methods)

The accurate liquid enzyme for weighing 0.25g immobilised enzymes or measuring 0.5ml, is added and contains 1g 6-APA and 1.25g D- In the 50ml phosphate buffers of HPM (0.1mol/L, pH6.30), pH to 6.3 is reconciled and with above-mentioned phosphate buffer constant volume To 100ml, at 25 DEG C, 20min is reacted with 0.1mol/l sodium hydroxide titration liquid perseverances pH6.3, records NaOH solution consumer Product, reaction finishes filters at once, takes 0.5mL filtrates to be settled to 100mL with mobile phase and carries out HPLC detections.

Pillar：Diamosil C185μm 4.6×250mm

Mobile phase：6.8g potassium dihydrogen phosphates are weighed, after adding the ultrapure water dissolutions of 956ml, with the NaOH solution liquid tune of 1mol/L PH to 5.8 adds 44ml chromatographic grade acetonitriles, degassing 20min or so after the water system membrane filtration in 0.22 μm of aperture.

Detection：UV 225nm

Sample size：20μL

Titer：Precision weighs the Amoxicillins 40mg standard items flowing phased soln and is settled to 200ml, and sampling carries out HPLC is detected.

Enzyme activity calculates

Enzyme activity unit (U) is defined as：Under certain reaction condition, the unit enzyme amount A Moxi per minute for generating 1 μm of ol Woods is 1U.

W is marked：Amoxicillin standard items weigh, mg；

P is marked：Amoxicillin standard items content, %；

A samples：Amoxicillin area in sample HPLC detections；

M：Amoxicillin molecular weight；

T：Reaction time, min；

V：Liquid enzyme sampling amount, ml；

W：Immobilised enzymes sample weighting amount, g；

m：Immobilised enzymes moisture, %.

(3) detection method of synthesis hydrolysis ratio (S/H values)

Reagent configuration, reaction condition and method are as shown in above-mentioned penicillin G acylase synthesis of dynamic assay method, reaction It finishes and filters at once, take 0.5mL filtrates to be settled to 100mL with mobile phase and carry out HPLC detections, record the molar consumption of 6-APA With D-pHPG (D-HPG) mole production quantity.

The production quantity (μm ol) of consumption (μm ol)/D-HPG of S/H values=6-APA

Embodiment 1：The preparation of low in hydrolysis vigor, high synthesis of dynamic SPGA mutant

By Fig. 1 reaction equations it is found that SPGA can either be catalyzed parent nucleus 6-amino-penicillanic acid (6-APA) with side chain D- to hydroxyl Phenylglycine methyl ester (D-HPM) synthetic product Amoxicillin, but energy hydrolysate generates parent nucleus and side chain, the invertibity of the reaction Size is decided by the equilibrium constant of the reaction；Meanwhile to be hydrolyzed into para hydroxybenzene by SPGA again sweet for p-hydroxyphenylglycine methyl ester Therefore propylhomoserin reduces the hydrolysis vigor of SPGA, improve its synthesis of dynamic and have great importance.

1-1 determines mutational site using the method for computer simulation

1-1-1 SPGA three dimensional joint elements

Utilize the blueness of the Escherichia coli (E.coli) and the source Bacillus foecalis alkaligenes (A.faecalis) that have measured three-dimensional structure Mycin G acylases are template, pass through SWISS-MODEL (http://swissmodel.expasy.org) online homologous modeling is soft Part models the penicillin G acylase in Achromobacter xylosoxidans source, is energy-optimised, marking and assessment, modeling are completed The penicillin G acylase protein three-dimensional structure in Achromobacter xylosoxidans source afterwards is as shown in Figure 2.

The foundation of 1-1-2 SPGA-Amoxicillin complex structures and the determination in mutational site

SPGA protein three-dimensional structures model and Amoxicillin are divided using molecular docking software Autodock4.0 Son docking, is carried out at the same time energy minimization and obtains SPGA-Amoxicillin complexs, the complex structure after optimization is shown in Fig. 3.

By Fig. 3's as a result, we select the points of the A162 near substrate binding pocket, B24 points, B71 points and B241 points for Pinpoint saturation mutation site.

1-2 SPGA mutant pinpoints the structure in saturation mutation library

In order to reduce the hydrolysis vigor of wild type SPGA, improves it and synthesize the vigor of Amoxicillin, the present inventor is with SPGA- WT is template, select on the α subunits near its substrate binding pocket the 162nd (A162 points), the 24th (B24 points) on β subunits, The 241st (B241 points) is fixed point saturation mutation site on (B71 points) and β subunits the 71st on β subunits, passes through full plasmid PCR Method structure fixed point saturation mutation library.Wherein respectively fixed point saturation mutation primer is as follows：

A162 point saturation mutation primers

P1：ATCGGCACCGCGAACCGCTTCTCTGACG (being saturation mutation site at underscore) (N be A or T or C or G, K are G or T)

P2：GCGGTTCGCGGTGCCGATGAAGATCAT (being saturation mutation site at underscore) (N be A or T or C or G, M are A or C)

B24 point saturation mutation primers

P3：GGCCCGCAG(N is A or T or C to GGCTGGTGGAATCCGGCC (being saturation mutation site at underscore) Or G, K are G or T)

P4：CCACCAGCCCTGCGGGCCGTTCAGCAG (being saturation mutation site at underscore) (N be A or T or C or G, M are A or C)

B71 point saturation mutation primers

P5：ACCGCGGGC(N is A or T or C to GGCGACGATGTCGACATC (being saturation mutation site at underscore) Or G, K are G or T)

P6：ATCGTCGCCGCCCGCGGTCGAGCCCCA (being saturation mutation site at underscore) (N be A or T or C or G, M are A or C)

B241 point saturation mutation primers

P7：GCCAACTGG(N is A or T or C to AACCAGCCGATGCGCGGC (being saturation mutation site at underscore) Or G, K are G or T)

P8：CGGCTGGTTCCAGTTGGCGATGAACCC (being saturation mutation site at underscore) (N be A or T or C or G, M are A or C)

Specific fixed point saturation mutation library constructing method is as follows：

Using SPGA-WT as template, using above-mentioned P1/P2, P3/P4, P5/P6 and P7/P8 as mutant primer, with full plasmid Round pcr carries out fixed point saturation mutation respectively to this 4 points, the KOD-Plus-Neo high-fidelity DNA polymerases used in wherein PCR And corresponding PCR buffer solutions, Mg²⁺, dNTPs solution buy in TOYOBO companies, and with reference to its specification carry out PCR reaction systems Configuration and PCR reaction conditions setting.

1-3 SPGA mutant pinpoints the screening in saturation mutation library

96 mutant clon are selected respectively to above-mentioned each mutant library and carry out preliminary screening, specially：It will be all prominent Varitron, which is inoculated in the 150ml shaking flasks of the culture mediums of LB containing 20ml, carries out fermentation and Fiber differentiation, is collected by centrifugation after 24 hours thin Born of the same parents, ultrasonication are simultaneously collected by centrifugation supernatant and obtain crude enzyme liquid, and by titration measuring, it hydrolyzes vigor, is measured by HPLC methods Its synthesis of dynamic；It will hydrolyze that vigor is low, the high muton of synthesis of dynamic carries out secondary screening choosing, specially：Above-mentioned muton is inoculated with (each muton is inoculated with 3 shaking flasks) carries out fermentation and Fiber differentiation in the 500ml shaking flasks of the culture mediums of LB containing 100ml, and surveys Fixed its hydrolyzes vigor and synthesis of dynamic, the good muton of effect be sequenced it is spare, specific each SPGA mutation vitality of subject and Mutating acid is as shown in table 2.

2 SPGA of table mutation vitality of subject and mutating acid

Enzyme	Hydrolysis vigor (U/ml)	Synthesis of dynamic (U/ml)
			SPGA-WT	26	4
Mα162L	22	7.3
			Fβ24G	16	6
Fβ71Y	20	7
			Nβ241Q	16	7.5

The preparation of 1-4 low in hydrolysis vigor, high synthesis of dynamic SPGA multipoint mutation bodies

As seen from the results in Table 2, N β 241Q mutant has lower hydrolysis vigor relative to wild type and other mutant With higher synthesis of dynamic, be named as SPGA-1, in order to obtain the better SPGA mutant of effect, the present inventor with SPGA-1 is template, respectively by M α 162L, F β 24G and F β 71Y with full plasmid pcr carry out fixed point saturation mutation be superimposed into On SPGA-1, double mutant, three point mutation and four point mutation are formed, are lived by the hydrolysis vigor and synthesis that measure each mutant Power chooses step experiment under the progress of best results, and specific each SPGA mutation vitality of subject and mutating acid are as shown in table 3.

3 SPGA of table mutation vitality of subject and mutating acid

As shown in Table 3, wherein four point mutation bodies (M α 162L, F β 24G, N β 241Q and F β 71Y) effect is best, and is ordered Entitled SPGA-2.

Embodiment 2：The preparation of acid resistance SPGA mutant

Since enzymatic clarification Amoxicillin carries out under condition of acidic pH, simultaneously because in industrial processes, it is green Mycin G acylases need continuous use 5 to 10 days, and this requires the enzymes to keep stabilization and not easy in inactivation under condition of acidic pH, And the acid resistance of wild type Penicillin G acylases is poor, therefore it is badly in need of a kind of novel PGA of tolerance acid pH of exploitation.To understand Certainly this problem in industrial production, the present inventor set new exploitation route, the SPGA-2 mutant best to said effect Further it is transformed.

The structure of 2-1 acid resistance SPGA random mutant libraries

In order to improve the acid resistance of SPGA, the present inventor is T7 universal primers (SEQ ID with SPGA-2 templates, wherein primer NO：13 and 14), a random mutant libraries are built by the method for fallibility PCR, and by adjusting fallibility PCR reaction systems Middle Mg²⁺And Mn²⁺Concentration and dCTP and dTTP oligonucleotides concentration, it is only thousand points to make the base mispairing rate of the mutant library Two, that is, ensure that a mutant only has 1 to 2 amino acid and mutates.The detailed process for building mutant library is as follows.

Fallibility PCR reaction systems：

Fallibility PCR reaction conditions are：First 95 DEG C of pre-degeneration 5min；Then 94 DEG C denaturation 30s, 56 DEG C annealing 1min, 72 DEG C Extend 1.5min, totally 25 cycles；Last 72 DEG C of extensions 10min.

Fallibility PCR product obtained above is subjected to electrophoresis and gel extraction purifying, by product and protokaryon table after purification NdeI and Xho I double digestions are carried out respectively up to carrier pET28b (+), and digestion carries out gel extraction in 3 hours respectively, by recovery product According to product：Carrier is 3：1 molar ratio is mixed, and T4DNA ligase are added in 16 DEG C of connections overnight.Second day, lead to The method for crossing chemical conversion, which is transferred in e. coli bl21 (DE3), builds engineering bacteria, you can obtains big random of a storage capacity Mutant library.

It is prepared by the high flux screening and mutant of 2-2 acid resistance SPGA mutant libraries

With the toothpick after high-temperature sterilization, the single bacterium colony in careful picking mutant library is inoculated in 96 equipped with LB culture mediums In porocyte culture plates, wherein LB culture volumes are for 200 holes μ L/ and containing the kanamycins of 50 μ g/ml, in 37 DEG C, It is cultivated in the constant-temperature table of 250rmp 8 hours, 1% lactose, 25 DEG C, Fiber differentiation 8 hours in the constant-temperature table of 250rmp. After induction, 96 porocyte culture plates are put into 2 hours of freeze thawing in -86 DEG C of ultra low temperature freezer, taking-up is positioned over room temperature Middle half an hour is placed in 96 porocyte culture plates centrifuges and is centrifuged 20 minutes in 4,000rmp, 4 DEG C.In above-mentioned enzyme solution, By 1：0.05mol/L is added in 2 volume ratios, and the phosphate buffer of pH 3.0 incubates 1 hour in 25 DEG C.

According to the high-throughput screening method in 103667418 A of Chinese patent application CN, sieved from above-mentioned mutant library About 20000 clones have been selected, have obtained 10 color changes obviously and the muton of numeric ratio SPGA-2 high.Then prominent to this 10 Varitron carries out secondary screening, and detailed process is：This 10 mutons are inoculated in the 500ml shaking flasks of the culture mediums of LB containing 100ml and are carried out Fermentation and induction, and its hydrolysis and synthesis of dynamic are measured by titration and HPLC methods, obtain 2 mutation better than control effect Son is respectively designated as PGA-3A and PGA-3B, shows that PGA-3A has occurred in the 64th site amino acids of β subunits by sequencing result Change, T has been mutated by A, and PGA-3B is changed in the 310th site amino acids of β subunits, and V has been mutated by A.

In order to further obtain the better SPGA mutation of acid resistance pH, the present inventor dashes forward above-mentioned A β 64T and A β 310V Variant is overlapped, and measures its hydrolysis vigor and synthesis of dynamic, by the six point mutation body (M α 162L, F β 24G, N β 241Q, F β 71Y, A β 64T and A β 310V) it is named as SPGA-4.Specific each acid resistance SPGA amino acid mutations point and mutation vitality of subject such as table Shown in 4.

4 acid resistance SPGA amino acid mutations point of table and mutation vitality of subject

Embodiment 3 recombinate SPGA albumen isolate and purify and immobilization

3-1 recombination SPGA albumen isolates and purifies

Due to introducing 2 of N-terminal and C-terminal in prokaryotic expression carrier pET28b (+) during expression vector establishment His-tag, therefore, the present inventor are carried out using the histidine tagImmobilization metal chelates affinity chromatography (IMAC)To purify weight Histone, the specific method is as follows.

SPGA zymotic fluids after taking 100mL to induce overnight, abandoned after centrifugation supernatant collect thalline (10000rpm, 4 DEG C, 10min), with phosphate buffer (pH 8.0,0.1mol/L), twice, thalline were collected by centrifugation for washing thalline repeatedly, concentrates 5 times of weights It is suspended from 20ml phosphate buffers (pH 8.0,0.1mol/L).Treated bacterium solution is placed in ice water and carries out ultrasound It is crushed until clarification, ultrasonication condition therein are：Work 2s, is spaced 5s.Above-mentioned broken lysate is placed in low temperature (12,000rpm, 4 DEG C, 20min) is centrifuged in supercentrifuge, collects supernatant, recombination SPGA albumen is obtained, by the big and heavy group of egg White sample introduction is to having activated and in conjunction with Ni⁺IDA resins on, carry out gradient elution with the imidazoles of gradient concentration, utilize protein chromatographic System (Bio-Rad) is monitored in real time, and when occurring stable protein peak in computer, starting collection, disappearance is until the peak Only.

Recombination zymoprotein, which is sealed in after isolating and purifying in sterile bag, is positioned over 4 DEG C of refrigerators in case subsequent experimental, simultaneously To this, zymoprotein carries out purity analysis with SDS-PAGE protein electrophoresis after purification, as a result sees Fig. 4.As seen from the figure, recombination SPGA It is made of two subunits of α, β, size respectively may be about 28kD and 63kD.

3-2 recombinates the immobilization of SPGA albumen

A, the activation of fixation support

Glutaraldehyde 30ml, the dipotassium hydrogen phosphate (K of accurate measurement 60%₂HPO₄·3H₂O) 4.76g be dissolved in 600ml go from In sub- water, it finally is settled to 1000ml with deionized water, while it is 8.0 to adjust its PH with phosphoric acid solution, it is spare after sterilizing；By ring Oxygroup carrier ECEP or amino carrier ECHA/S (Italian ResindionS.r.l companies) 250g are put into above-mentioned solution, and 2h is activated in 25 DEG C of stirring at low speed, carrier is collected by filtration, vacuum is filtered dry standby after being used in combination aseptic deionized water to rinse 2~3 times repeatedly With.

B, enzyme immobilizatio

A certain amount of above-mentioned enzyme solution after purification is taken, is dissolved with phosphate buffer (pH 8.0,0.1mol/L), is then added 50g is activated treated carrier, the stirring at low speed immobilization 48h under the conditions of 25 DEG C, 120rpm spend gained immobilised enzymes Ionized water cleans 3~5 times repeatedly, and vacuum is filtered dry rear up to immobilised enzymes finished product.It is accurate weigh the above-mentioned immobilised enzymes of 1g (with For SPGA-WT) vigor and synthesizing activity measurement is hydrolyzed, using ECEP and ECHA/S as the immobilized enzyme hydrolysis enzyme activity of carrier Respectively 262U/g and 239U/g, synthesizing activity are respectively 45U/g and 34U/g, and epoxy base carrier ECEP immobilized enzymes are bright It is aobvious to be higher than amino carrier ECHA/S immobilised enzymes, therefore select epoxy base carrier ECEP as the fixation support of SPGA.

The property of 4 mutant SPGA-4 immobilised enzymes of embodiment and its application for preparing Amoxicillin

The property of 4-1 mutant SPGA-4 immobilised enzymes

Protein purification, immobilization are carried out to above-mentioned wild type and saltant type SPGA according to the method for embodiment 4, meanwhile, point Not Ce Ding immobilised enzymes hydrolysis and synthesis of dynamic and S/H values, mutant SPGA-4 immobilised enzymes and other muton immobilizations The Nature comparison of enzyme is shown in Table 5.

5 wild type of table and saltant type SPGA immobilised enzymes Nature comparisons

Enzyme	Hydrolysis vigor (U/g)	Synthesis of dynamic (U/g)	S/H values
				SPGA-WT	262	45	2.1
SPGA-1	169	73	4.3
				SPGA-2	101	142	10.8
SPGA-3A	79	153	13.4
				SPGA-3B	68	169	14.7
SPGA-4	30	212	16.8

As shown in Table 5, mutant SPGA-4 immobilised enzymes declines relative to wild type SPGA immobilised enzymes, hydrolysis vigor 8.7 times, synthesis of dynamic improves 5.6 times, and S/H values improve 8 times, illustrate the mutant immobilised enzymes relative to wild type SPGA immobilised enzymes has better Amoxicillin synthesis performance, not facile hydrolysis side chain and product Amoxicillin.

4-2 mutant SPGA-4 immobilised enzymes acid resistances are tested

By above-mentioned wild type and saltant type SPGA immobilised enzymes, it is respectively placed in identical enzyme amount (200U synthesis of dynamic) In the buffer solution of pH2.0, pH3.0, pH4.0, pH5.0, pH6.0 and pH7.0,1 hour is incubated in 25 DEG C, takes out immobilization afterwards Enzyme is rinsed 4~5 times repeatedly with aseptic deionized water, and to ensure to incite somebody to action there is no buffer solution residual in immobilised enzymes, treated consolidates Surely change enzyme and measure its remaining vigor with HPLC methods, concrete outcome is as shown in table 6.

6 wild type of table and saltant type SPGA immobilised enzymes acid pH tolerances compare

According to 6 result of table it is found that SPGA-4 immobilised enzymes also keeps about 80% vigor under the conditions of pH2.0, in pH3.0 Under the conditions of keep 86% vigor, under the conditions of 7.0 pH4.0-activity do not change substantially, show the enzyme in acid condition It keeps stablizing.

4-3 mutant SPGA-4 immobilised enzymes prepares the application of Amoxicillin

(1) 10 DEG C of solid process

210ml is preheated to 10 DEG C of pure water in advance to pour into equipped with 2000U mutant SPGA-4 immobilised enzymes (with wild type SPGA immobilised enzymes be control) beaker in, 21.0g6-APA the and 18.3g D-HPM solids for being directly added into accurate weighing (rub You are than being 1：1.04) to reaction system, stirring is opened, 10 DEG C of reactions are maintained；In conversion process, 10 DEG C of controlling reaction temperature, PH is not required to.

Endpoint：When declining 0.02 after pH value peaks, you can terminate reaction.

(2) 20 DEG C of solid process

230ml is preheated to 20 DEG C of pure water in advance to pour into equipped with 1800U mutant SPGA-4 immobilised enzymes (with wild type SPGA immobilised enzymes is control) beaker in, 20.0g6-APA the and 17.09g D-HPM solids of accurate weighing are added without molten Solve (molar ratio 1：1.02) to reaction system, stirring is opened, 20 DEG C of reactions are maintained；In conversion process, controlling reaction temperature 20 DEG C, pH is not required to.

(3) Amoxicillin crystallization reaction

After reaction terminating, washing, which filters out immobilised enzymes and washs filtering repeatedly with reaction mother liquor, is collected into whole A Moxi Woods coarse powder quickly dissolves Amoxicillin with 6mol/L hydrochloric acid tune pH, is filtered to remove insoluble impurities, and growing the grain about 5 minutes slowly adds Enter 6mol/L ammonium hydroxide tune pH value to 5.0 ± 0.1, is cooled to 1~4 DEG C, growing the grain about 20min, powder collected by filtration.It is taken out with vacuum Dry be placed in drier is dried overnight, after pack of weighing, detection Amoxicillin moisture, content and 6-APA and D-HPM conversions Rate prepares the HPLC collection of illustrative plates of Amoxicillin synthesis referring to Fig. 5, specific experiment correction data using mutant SPGA-4 immobilised enzymes It is shown in Table 7.

7 wild type SPGA of table and saltant type SPGA-4 immobilised enzymes Transformation Application Experimental comparisons

Enzyme	Reaction temperature (DEG C)	Reaction time (min)	Conversion ratio
				SPGA-WT	10	120	87.3%
SPGA-4	10	80	99.2%
				SPGA-WT	20	105	89.2%
SPGA-4	20	60	99.3%

As shown in Table 7, mutant SPGA-4 immobilised enzymes reaction 6-APA and D-HPM conversion ratio up to 99% with On, the reaction of Amoxicillin is synthesized under same reaction condition with wild type SPGA immobilized enzyme catalysis, 6-APA and D-HPM's Conversion ratio is not achieved 90%.

4-4 mutant SPGA-4 immobilised enzymes operational stability batches are tested

In order to preferably reflect that the stability of the mutant, the present inventor during the experiment set its reaction condition such as Under：The total throwing amount of SPGA-4 immobilised enzymes (212U/g) is 8000U, and substrate 6-APA and D-HPM solid molar ratio is 1：1.02 instead PH is answered to be not required to, reaction temperature is 20 DEG C, and reaction volume 1000ml, the results are shown in Table 8 for specific experiment.

8 mutant SPGA-4 immobilised enzymes operational stability batches of table are tested

By the experiment of SPGA-4 immobilised enzymes operational stability batches it is found that SPGA-4 immobilised enzymes warp prepared by the present invention Continuous 300 batch transformation experiment is crossed, the reaction time is not obviously prolonged, and immobilized enzyme is not decreased obviously, and is shown Mutant SPGA-4 immobilised enzymes prepared by the present invention has good operational stability.

Each mutant SPGA of the present invention can also be applied to prepare ammonia benzyl west other than it can be applied to synthesis Amoxicillin The semi-synthetic beta-lactam antibiotic such as woods, cefalexin, cefadroxil, Cefaclor and Cefradine；The present invention simultaneously Do not limited by above-mentioned specific verbal description, the present invention can in the range of claims are summarized essence according to the present invention God does various changes.These changes are all within the scope of the present invention.

Claims

1. penicillin G acylase mutant, which is characterized in that it is in Achromobacter xylosoxidans（Achromobacter xylosoxidans）Wild type Penicillin G has following arbitrary mutation on the basis of being acylated enzyme amino acid sequence：

1）The 241st amino acids sport Q by N on β subunits；

2）The 162nd amino acids sport the 241st amino acids on L and β subunits by M and sport Q by N on α subunits；

3）The 24th amino acids sport the 241st amino acids on G and β subunits by F and sport Q by N on β subunits；

4）The 71st amino acids sport the 241st amino acids on Y and β subunits by F and sport Q by N on β subunits；

5）The 162nd amino acids sport the 241st amino acids on L, β subunit by M and are sported on Q and β subunits by N on α subunits 24th amino acids sport G by F；

6）The 162nd amino acids sport the 241st amino acids on L, β subunit by M and are sported on Q and β subunits by N on α subunits 71st amino acids sport Y by F；

7）The 162nd amino acids sport the 24th amino acids on L, β subunit by M and are sported on G, β subunit by F on α subunits 241 amino acids sport the 71st amino acids on Q and β subunits by N and sport Y by F；

8）The 162nd amino acids sport the 24th amino acids on L, β subunit by M and are sported on G, β subunit by F on α subunits 241 amino acids sport on Q, β subunit the 71st amino acids by N and sport on Y and β subunits the 310th amino acids by A by F Sport V；

9）The 162nd amino acids sport the 24th amino acids on L, β subunit by M and are sported on G, β subunit by F on α subunits 241 amino acids by N sport the 71st amino acids on Q, β subunit and sport the 64th amino acids on Y and β subunits by F is dashed forward by A Become T；

10）The 162nd amino acids sport the 24th amino acids on L, β subunit by M and are sported on G, β subunit by F on α subunits 241 amino acids by N sport the 71st amino acids on Q, β subunit and sport the 310th amino acids on Y, β subunit by F is dashed forward by A Become the 64th amino acids on V and β subunits and T is sported by A；

The Achromobacter xylosoxidans wild type Penicillin G is acylated the α that enzyme amino acid sequence is made of 232 amino acid The β subunit three parts of intermediate connection peptide and 557 amino acid compositions that subunit, 54 amino acid form are constituted, sequence such as SEQ Shown in ID NO.1.

2. encoding the gene of mutant described in claim 1.

3. application of the penicillin G acylase mutant described in claim 1 in preparing Amoxicillin.

4. application of the penicillin G acylase mutant according to claim 3 in preparing Amoxicillin, feature exist In, specifically using penicillin G acylase mutant immobilised enzymes as catalyst, using 10 DEG C or 20 DEG C of solid process catalyze and synthesize Ah Amdinocillin, wherein substrate 6-amino-penicillanic acid and the direct solid of D-pHPG feed intake, and pH is not necessarily in reaction process Control, it is only necessary to which controlling reaction temperature is 10 DEG C or 20 DEG C；

The penicillin G acylase mutant is in Achromobacter xylosoxidans wild type Penicillin G acylase amino acid There is following mutation in sequence basis：The 162nd amino acids sport the 24th amino acids on L, β subunit by M and are dashed forward by F on α subunits Become the 241st amino acids on G, β subunit and sport the 71st amino acids on Q, β subunit by N being sported on Y, β subunit by F 310 amino acids sport the 64th amino acids on V and β subunits by A and sport T by A.