WO2007016861A1 - Procédé enzymatique en deux étapes pour préparer un acide 7-aminocéphalosporanique - Google Patents
Procédé enzymatique en deux étapes pour préparer un acide 7-aminocéphalosporanique Download PDFInfo
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- WO2007016861A1 WO2007016861A1 PCT/CN2006/001940 CN2006001940W WO2007016861A1 WO 2007016861 A1 WO2007016861 A1 WO 2007016861A1 CN 2006001940 W CN2006001940 W CN 2006001940W WO 2007016861 A1 WO2007016861 A1 WO 2007016861A1
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- amino acid
- glutaryl
- acid oxidase
- aminocephalosporanic
- acylase
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P35/00—Preparation of compounds having a 5-thia-1-azabicyclo [4.2.0] octane ring system, e.g. cephalosporin
- C12P35/02—Preparation of compounds having a 5-thia-1-azabicyclo [4.2.0] octane ring system, e.g. cephalosporin by desacylation of the substituent in the 7 position
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- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
- C12N9/0004—Oxidoreductases (1.)
- C12N9/0012—Oxidoreductases (1.) acting on nitrogen containing compounds as donors (1.4, 1.5, 1.6, 1.7)
- C12N9/0014—Oxidoreductases (1.) acting on nitrogen containing compounds as donors (1.4, 1.5, 1.6, 1.7) acting on the CH-NH2 group of donors (1.4)
- C12N9/0022—Oxidoreductases (1.) acting on nitrogen containing compounds as donors (1.4, 1.5, 1.6, 1.7) acting on the CH-NH2 group of donors (1.4) with oxygen as acceptor (1.4.3)
- C12N9/0024—D-Amino acid oxidase (1.4.3.3)
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
- C12P35/00—Preparation of compounds having a 5-thia-1-azabicyclo [4.2.0] octane ring system, e.g. cephalosporin
- C12P35/06—Cephalosporin C; Derivatives thereof
Definitions
- the present invention relates to the field of bioengineering technology, and in particular to a two-step enzymatic process for the preparation of 7-aminocephalosporanic acid. Background technique
- Semi-synthetic cephalosporin core 7-aminocephalosporanic acid can be prepared by chemical method from cephalosporin C.
- chemical methods require the use of a large number of toxic preparations, which pollute the environment, and have low yield and high cost.
- the preparation of fine chemicals by enzymatic methods is an emerging process in recent years, which avoids the use of toxic preparations and has a high yield.
- Enzymatic preparation of 7-aminocephalosporanic acid involves two steps (see Figure 1): (1) D-amino acid oxidase oxidizes cephalosporin C to glutaryl-7-aminocephalosporin (glutaryl-7- (2) Glutaryl-7-aminocephalosporanic acid acylase hydrolyzes glutaryl-7-aminocephalosporanic acid to produce 7-aminocephalosporanic acid.
- -7-Aminocephem citrate ( a - ketoadipyl-7- ACA) cannot be converted to glutaryl-7-aminocephalosporanic acid, so it needs to be converted to glutaryl-7-amino head with the addition of hydrogen peroxide.
- hydrogen peroxide will oxidize cephalosporin C and glutaryl-7-aminocephalosporanic acid, and the final 7-aminocephalosporin The acid yield is reduced, so that additional catalase is required to degrade the residual hydrogen peroxide.
- An object of the present invention is to provide a two-step enzymatic process for the preparation of 7-aminocephalosporanic acid which is simple in procedure, low in cost and high in yield.
- the technical solution of the present invention provides a method for preparing 7-aminocephalosporanic acid from cephalosporin C, which comprises catalyzing cephalosporin C to glutaryl-7-amino group with D-amino acid oxidase.
- the D-amino acid oxidase is a purified Trigonopsis variabilis D-amino acid oxidase mutant having the amino acid sequence of SEQ ID NO: 2.
- the first step reaction is not added.
- Hydrogen peroxide it is further preferred that the D-amino decanoate oxidase is expressed by the expression vector pHS-GHA having the DNA sequence of SEQ ID NO: 3, and the purification step of the D-amino acid oxidase comprises sequentially passing the DEAE-fiber
- the ion exchange resin was purified and purified by ammonium sulfate precipitation.
- the D-amino acid oxidase is immobilized, or the glutaryl-7-aminocephalosporanic acid acylase is immobilized, or D-amino acid oxidase and glutaryl - 7-aminocephalosporanic acid acylases are all solid phased.
- the glutaryl-7-aminocephalosporanic acid acylase is Pseudomonas sp.
- SE83 glutaryl-7-aminocephalosporanic acid acylase, said Monospora SE83 glutaryl-7-aminocephalosporanic acid acylase is expressed by the expression vector pT7-kan-ACY having the DNA sequence shown in SEQ ID NO:4
- the present invention has the advantages of: (1) a purified Trigonopsis variabi lis D-amino acid oxidase mutant having the amino acid sequence of SEQ ID NO: 2 in the method of the present invention, the specific ratio of the parent D-amino acid The oxidase is 105% higher; (2) the E. coli vectors pHS-GHA and pT7-kan- ACY in the method of the present invention do not contain ⁇ -lactamase in the fermentation product, so no additional ⁇ -lactamase inhibitor is required , reducing production costs and simplifying the process; (3) in the method of the invention!
- the amino acid oxidase contains almost no catalase, so no additional catalase inhibitor is required, and the production of ⁇ -ketoadipylic acid-7-aminocephalosporanic acid is low during the reaction. Therefore, it is not necessary to add hydrogen peroxide and catalase, which reduces production cost and simplifies the process; (4) Transformation of cephalosporin C to 7-aminocephalosporanic acid by the two-step solid phase enzymatic method of the present invention;
- the molar conversion rate can reach more than 93%, which is about 12% lower than that of Roche Diagnostics (the molar conversion rate is 82%).
- Figure 1 shows the reaction scheme for the conversion of the current cephalosporin C to 7-aminocephalosporanic acid.
- Figure 2 shows the expression vector pHS-GHA.
- Figure 3 shows the expression vector pT7- kan- ACY.
- Figure 4 shows the expression vector pRSET- lac- GI- hok/sok- kan.
- Figure 5 is a SDS-PAGE electropherogram of the D-amino acid oxidase mutant GHA.
- 1 stands for: BenchmarkTM Pre-Stained Protein Ladder (Invitrogen), the unit is KDa; 2 stands for: crude pure D-amino acid oxidase mutant GHA; 3 stands for: purified D-amino acid oxidase mutation Body GHA.
- Figure 6 is a HPLC chromatogram of D-amino acid oxidase mutant GHA-transformed cephalosporin C to glutaryl-7-aminocephalosporanic acid.
- Figure 7 is a SDS-PAGE electropherogram of Pseudomonas sp. SE83 glutaryl-7-aminocephalosporanic acid acylase.
- 1 represents: BenchmarkTM Pre-Stained Protein Ladder (Invitrogen), the unit is KDa; 2 represents: Pseudomonas aeruginosa SE83 glutaryl -7-aminocephalosporanic acid acylase.
- Figure 8 is a HPLC chromatogram of the conversion of glutaryl-7-aminocephalosporanic acid to 7-aminocephalosporanic acid by Pseudomonas sp. SE83 glutaryl-7-aminocephalosporanic acid acylase.
- Figure 9 is a HPLC chromatogram of a two-step solid phase enzyme conversion of cephalosporin C to 7-aminocephalomycin. detailed description
- PCR primers were designed based on the sequence of pRSET-A (available from Invitrogen), specifically:
- Upstream bow object VET-F 5, - CTGTCAGACCAAGTTTACTCATATATACTTTAG - 3, ;
- Downstream bow object VET- R 5, - ACTCTTCCTTTTTCAATATTATTGAAGC-3, 0
- PCR primers were designed according to the sequence of pET28b (available from Novagen), specifically the upstream primer KAN-F: 5, - ATGAGCCATATTCAACGGGAAAC- 3;
- Downstream primer KAN- R 5, -TTAGAAAAACTCATCGAGCATCAAATG-3 '.
- the PCR conditions for amplification of the pRSET-A fragment of the ampicillin resistance gene were: 50 ng pRSET-A (Invitrogen), 0.4 ⁇ M VET-F, 0.4 ⁇ VET-R, 50 ⁇ dATP, 50 ⁇ dTTP , 50 ⁇ dCTP, 50 ⁇ dGTP, 20 mM Tris-HCl (pH 8. 8 ), 10 mM KC1 , 10 mM (NH 4 ) 2 S0 4 , 2 mM MgS0 4 , 0.1% Triton X-100, 2.5 U Pfu DNA polymerase (Promega), adjust the reaction volume to 50 ⁇ with sterile water.
- the PCR amplification reaction procedure was: 94 ° C, 5 minutes; 94 ° C, 1 minute, 5 Q ° C, 1 minute, 72 ° C, 4 minutes, 35 cycles; 72 ° C, 10 minutes.
- the PCR conditions for amplifying the kanamycin resistance gene were: 50 ng pET28b (Novagen), 0.4 ⁇ KAN-F, 0.4 ⁇ KAN-R, 50 ⁇ dATP, 50 ⁇ dTTP, 50 ⁇ dCTP, 50 ⁇ , 20 mM Tris ⁇ HCl (pH 8.8), 10 mM KCl, 10 mM (NH 4 ) 2 S0 4 , 2 mM MgS0 4 , 0.1% Triton X-100, 2.5 U Pfu DNA polymerase (Promega), adjusted reaction volume with sterile water Up to 50 L.
- the PCR amplification reaction procedure was: 94 ° C, 5 min; 94 ° C, 1 min, 50 ° (, 1 min, 72 ° C, 4 min, 35 cycles; 72 ° C, 10 min.
- the PCR product was purified by electrophoresis on 0.8% agarose (the PCR product of the pRSET-A fragment of the ampicillin resistance gene was removed by 2, 036 bp; the PCR product of the kanamycin resistance gene was 816 bp), and the two fragments were ligated.
- pRSET- kan Transformation of pRSET-kan into competent E. coli BL21(DE3)pLysS (Novagen) in kanamycin (50 g/mL) LB
- PCR primers were designed according to the sequence of pGEMT-Easy (Promega), specifically: upstream primer RBS- Ndel: 5, - CATATGTATATCTCCTTCTTGTGTGAAATTG-3,
- Downstream primer RBS- Al wNI 5 ' -CAGTGGCTGCTGCCAGTGGCGATAAGTC-3,
- PCR was carried out using the above primers to obtain a 755 bp product.
- the PCR conditions were: 50 ng pGEMT- Easy (Promega), 0.4 ⁇ RBS- Ndel, 0.4 ⁇ RBS-AlwNI, 50 ⁇ dATP, 50 ⁇ dTTP, 50 ⁇ dCTP, 50 ⁇ dGTP, 20 mM Tris-HC1 (pH 8.8) , 10 mM KC1, 10 mM (leg 4 ) 2 S0 4 , 2 mM MgS0 4 , 0.1% Triton X - 100, 2.5 U Pfu DNA polymerase (Promega), adjust the reaction volume to 50 ⁇ ⁇ PCR with sterile water
- the reaction increase procedure is: 94 ° C, 5 minutes; 94 ° C, 1 minute, 50, 1 minute, 72 ° C, 4 minutes, cycle 35 times; ⁇ 2 ⁇ , 10
- the PCR product (755 bp) contains a Ndel restriction site and a ribosome binding site at the 5' end and an AlwNI restriction site at the 3' end.
- Ndel and AlwNI were digested, and ligated with pRSETA (Invitrogen) digested with Ndel and AlwNI to obtain pRSET-lac.
- pRSET-lac was transformed into competent E. coli BL21(DE3)pLysS (Novagen) on a plate of ampicillin (100 g/mL) LB (1% sodium chloride, 1°/. peptone, 0.5% yeast extract) Incubate overnight at 37 °C.
- the plasmid was extracted according to the method described in Molecular Cloning - A Laboratory Manual (Sambrook, J. et al., 1989, CSHL Press).
- pRSET-lac and pRSET-kan were digested with AlwNI and EcoRI, and each DNA fragment was purified by 0.8% agarose electrophoresis and ligated to obtain pRSET-lac-kan.
- pRSET-lac-kan was transformed into competent E. coli BL21(DE3)pLysS (Novagen) and cultured on kanamycin (50 g/mL) LB agar plates overnight at 37 °C. The plasmid was extracted according to the method described in Molecular Cloning-A Laboratory Manual (Sambrook, J. et al., 1989, CSHL Press).
- Example 3 Construction of vector pGEMT- Easy-GI
- the PGR primer was designed according to the known Thermoanaerobac terium sa c charoly ticum glucose isomerase DNA sequence (GenBank L09699), specifically: upstream primer (GI-Ndel):
- Downstream primer (GI- EcoRI): 5, - GATATCTTAAGGCGCGCCTTATTCTGCAAAC- 3,
- PCR was carried out using the above primers to obtain a 1,336 bp product.
- the PCR conditions were: 50 ng T.
- the PCR amplification protocol is: 95 ° C, 5 minutes; 94 ° C, 1 minute, 50 ° C, 1 minute, 72 ° C, 3 minutes, 35 cycles; 72 ° C, 10 minutes.
- the PCR product (1,336 bp) contained Ndel and EcoRI cleavage sites at the 5' and 3' ends, respectively.
- the PCR product was purified by 0.8% agarose electrophoresis, and ligated with pGEMT-Easy (Promega) by TA cloning to obtain pGEMT-Easy-GI.
- pGEMT-Easy-GI was transformed into competent E.
- pGEMT-Easy-GI was digested with Ndel and EcoRI, purified by 0.8% agarose electrophoresis, and ligated with pRSET-lac-kan digested with Ndel and EcoRI to obtain pRSET-lac-GI-kan.
- pRSET-lac-GI-kan was transformed into competent E. coli BL21 (DE3) pLysS (Novagen) and cultured on kanamycin (50 g/mL) LB agar plates overnight at 37 °C. The plasmid was extracted according to the method described in Molecular Cloning - A Laboratory Manual (Sambrook, J. et al., 1989, CSHL Press).
- the PCR conditions were: 20 ng each primer, 50 ⁇ dATP, 50 ⁇ dTTP, 50 lean dCTP, 50 ⁇ dGTP, 20 mM Tris-HCl (pH 8.8), lOmMKCl, 10 mM (N3 ⁇ 4) 2 S0 4 , 2mMMgS0 4 , 0.1% Triton X-100, 2.5 U Pfu DNA Polymerase (Promega), adjust the reaction volume to 50 ⁇ with sterile water.
- the PCR amplification reaction procedure was: 95 ° C, 4 minutes; 94 ° C, 1.5 minutes, 50 ° C, 1.5 minutes, 72. C, 5 minutes, 30 cycles; 72 ° C, 10 minutes, a PCR product was 580 bp long, containing Ascl and EcoRI cleavage sites at the 5' and 3, respectively.
- the PCR product was purified by 0.8% agarose electrophoresis. After digestion with Ascl and EcoRI, it was ligated with pRSET-lac-GI-kan digested with Ascl and EcoRI to obtain pRSET-lac-GI-hok/s. K- kan. pRSET-lac-GI-hok/sok-kan was transformed into competent E.
- Example 5 Construction of recombinant plasmid pRSET-A-DAO containing D-amino acid oxidase gene According to the 5' and 3' end sequences of the known D-amino acid oxidase gene of Trichoderma (Gonzalez, FJ, Montes, J., Martin, F., Lopez, MC, Ferminan E., Catalan, J. , Galan, MA Dominguez, A. Molecular cloning of TvDAOl, a gene encoding a D - amino acid oxidase from Trichoderma (Gonzalez, FJ, Montes, J., Martin, F., Lopez, MC, Ferminan E., Catalan, J. , Galan, MA Dominguez, A. Molecular cloning of TvDAOl, a gene encoding a D - amino acid oxidase from Trichoderma (Gonzalez, FJ, Montes, J.,
- Trigonopsis variabilis and its expression in Sa c ch aromyc es cerevisiae and Kluyveromyces lac t is. Yeast 13: 1399-1408;
- the PCR amplification reaction procedure was: 94 ° C, 5 minutes; 94 ° C, 1 minute, 50 ° C, 1 minute, 72 ° C, 2 minutes, 10 cycles; 94 ° C, 1 minute, 60 ° C, 1 minute, 72 ° C, 2 minutes, cycle 25 times; 72 ° C, 10 minutes.
- a 1,098 bp long PCR product was obtained with Ndel and Bglll restriction sites at the 5' and 3' ends, respectively.
- the PCR product was purified by 1% agarose electrophoresis, digested with Ndel and Bglll, and ligated with the 2.9 Kb fragment obtained by Ndel and Bglll digestion of plasmid pRSET-A (Invitrogen) to obtain the ligated product pRSET-A-DA0.
- pRSET-A-DAO was transformed into competent E. coli BL21(DE3)pLysS (Novagen) and cultured on ampicillin LB plate at 37 ° C according to Molecular Cloning-A Laboratory Manual, ed. By J.
- the D-amino acid oxidase mutant GHA was constructed from site-directed mutagenesis.
- Site-directed mutagenesis technology main reference PCR Protocols (Editor: John M. S. Bartlett and David
- Primer A 5, -TAGGGCTGACATATGGCTAAAATCGTTGTTATTG -3, ;
- Primer B 5, -TAGGGCTGAAGATCTCTAAAGGTTTGGACGAG -3, ;
- Primer C1 5'-GCAGGTGCCAACTGGCTCCCGTTTTACGATGGAGGCAAG-3'; Primer D: 5, -GAGCCAGTTGGCACCTGCCCAAGG-3 '.
- Primers A and B are an external primer.
- Primer A contains a Ndel restriction site, and some of the bases overlap with the 5' end of the D-amino acid oxidase gene;
- primer B contains a Bglll cleavage site, and has a partial base and D-amino acid oxidase. The 3' end of the gene overlaps.
- Primers C1 and D are internal primers. Primer C1 converts the threonine at position 53 of the parent D-amino acid oxidase gene into a proline. The base of the primer D overlaps with the sequence of the primer C1.
- template fragment 1 was amplified with primer pairs A and D using pRSET-A-DA0 as a template; template fragment 2 was amplified with primer pairs B and C1.
- the amplification reaction conditions were: 20 ng pRSET-A-DAO, 20 mM Tris-HCl (pH 8.8), 10 mM KC1, 10 mM (NH 4 ) 2 S0 4 , 2 mM MgS0 4 , 0.1% Triton X-100, 0.4 ⁇ Primer A and 0.4 ⁇ Primer D (amplification template fragment 1) or 0.4 ⁇ primer and 0.4 ⁇ primer C1 (amplification template fragment 2), 50 ⁇ dATP, 50 ⁇ dTTP, 50 ⁇ dCTP, 50 ⁇ dGTP, 1.5 U Pfu DNA polymerase, adjust the reaction volume to 50 ⁇ l with sterile water.
- the polymerase chain reaction amplification procedure was: 94 ° C, 2 minutes; 94 ° C,
- the amplified template fragment 1 and template fragment 2 were separated and purified by 1% agarose gel electrophoresis to amplify the full-length gene.
- the reaction conditions for amplifying the full-length gene were: 20 ng of template fragment 1, 20 ng of template fragment 2, 20 mM Tris-HCl (pH 8.8), 10 mM KCl, 10 mM ( ⁇ 4 ) 2 S0 4 , 2 mM MgS0 4 , 0.1% Triton X - 100, 0.4 ⁇ Primer A and 0.4 ⁇ primer, 50 ⁇ dATP, 50 ⁇ dTTP, 50 ⁇ dCTP, 50 ⁇ dGTP, 1.5 U Pfu DNA polymerase, adjust the reaction volume to 50 ⁇ l with sterile water. Polymerase chain The reaction amplification procedure was: 94 ° C, 2 minutes; 94 ° C, 1 minute, 53 ° C, 1 minute, 72 ° C, 2 minutes, 35 cycles; 72 ° C, 10
- the full-length amplification reaction obtained the D-amino acid oxidase mutant GHA gene, which was digested with Ndel and Bglll, ligated into pRSET-kan to obtain the ligation product pRSET- kan-DA0GHA, and pRSET-kan-DA0GHA was transformed into competent E. coli BL21 ( DE3) pLysS, kanamycin LB plate cultured at 37 ° C, plasmid was extracted, and the introduced mutation was confirmed by DNA sequencing.
- the DNA sequence of D-amino acid oxidase mutant GHA was determined as shown in SEQ ID NO: 1, which was inferred.
- the amino acid sequence is shown in SEQ ID NO: 2.
- Example 7 Construction of vector pHS-GHA (see Figure 2)
- the plasmid RSET-kan-DAOGHA was digested with Ndel and Bgl ll to obtain a 1,074 bp gene fragment (containing the D-amino acid oxidase mutant GHA gene), purified by 0.8% agarose electrophoresis, and transfected with Ndel and Bgl.
- the long fragment obtained by pl-cut pRSET-lac- GI-hok/sok-kan was ligated to obtain pHS-GHA.
- the pHS-GHA was transformed into competent E.
- Upstream primer (Ndel-ACY): 5, -CATATGAACGCTCCCGTCCCCGTCCC-3 ', Ndel restriction sites are underlined;
- Downstream primer (Bglll-ACY): 5, -AGATCTTCAGATGGTGAAGCGGGCAC-3, , Bglll cleavage site is underlined.
- Pseudomonas sp. SE83 DNA was carried out using the above primers, and amplification was obtained. A 1,676 bp product.
- the PCR conditions were: 50 ng Pseudomonas SE83 DNA, 0.4 ⁇ Ndel-ACY, 0.4 ⁇ Bglll-ACY, 50 ⁇ dATP, 50 ⁇ dTTP, 50 ⁇ dCTP, 50 ⁇ , 20 mMTris-HCl (pH 8.8), 10 mM KCl, 10 mM (leg 4 ) 2 S0 4 , 2 mMMgS0 4 , 0 ⁇ 1% Triton X-100, 2.5 U Pfu DNA polymerase (Promega), adjust the reaction volume to 50 ⁇ with sterile water.
- the PCR amplification reaction procedure was: 95 ° C, 5 min; 94 ° C, 1 min, 50 ° C, 1 min, 72 D C, 3 min, 35 cycles; 72 ° (:, 10 min.
- the PCR product (1,676 bp) contains Ndel and Bglll cleavage sites at the 5' and :T ends, respectively.
- the PCR product was purified by 0.8% agarose electrophoresis, digested with Ndel and Bglll, and ligated with pRSET-kan digested with del and Bglll to obtain pT7-kan-ACY.
- pT7-kan-ACY was transformed into competent E. coli BL21(DE3)pLysS (Novagen), and the strain BL-T7K-ACY was obtained and cultured on kanamycin (50 ⁇ g/mL LB agar plate at 37 ° C overnight).
- the above precipitate was redissolved in 600 mL of distilled water, stirred and centrifuged (5 000 g, 8 minutes), and the supernatant was corn syrup 2.
- the weight of each component in 50 mL seed medium is as follows
- the weight of each component in the 2L fermentation medium is as follows:
- the sterilized glucose and magnesium sulfate were placed in a 2 L fermentor before fermentation.
- the bacteria were separated by centrifugation at 4,000 ° C (5,000 g, 8 minutes), and the supernatant was discarded to obtain 220 g of bacteria (wet weight), and the bacteria were resuspended in 600 mL of sodium phosphate buffer ( 50 mM, pH 7.5).
- the bacteria were lysed by bead milling, and the bacterial suspension was sent to a bead mill (DYNO-MIL TYP KDL, 0.2 mm diameter glass beads, WA Bachofen) at a rate of 50 mL per minute, and finally buffered with 800 mL of sodium phosphate.
- the bacteria residue 50 mM, pH 7.5 was flushed out.
- the bacterial lysate was immersed in a 55 ° C water bath for 30 minutes, centrifuged at high speed (10,000 g, 30 minutes), and the supernatant was taken as a crude D-amino acid oxidase mutant GHA. Samples were taken and the purity and content of the target protein were determined by SDS-PAGE (see Figure 5). As shown, the crude D-amino acid oxidase mutant GHA accounts for approximately 40% of the total soluble protein.
- Example 11 D-amino acid oxidase mutant GHA purification
- Example 10 Take the crude pure D-amino acid oxidase mutant GHA extracted in Example 10, add glycerin to a final concentration of 10%, adjust the pH to 8 with 5N sodium hydroxide, centrifuge (13,000 g, 30 minutes), take The supernatant.
- DEAE-cellulose ion exchange resin (Sigma, D-0909) was supplied according to the product preparation method described by the product supplier. 0.5raL DEAE-cellulose ion exchange resin per 1mL of crude pure enzyme, stirred at 4 ° C for 5 hours (100 rpm), with filter (Buchner filter funnel, 120 mm PI) The enzyme solution was filtered off.
- the method is basically as described in Isogai, T, et al., 1990, J. Biochem. [Tokyo] 108 1063- 1069, wherein the specific steps are changed.
- the D-amino acid oxidase mutant GHA purified as in Example 11 was diluted 10-fold with sodium phosphate buffer (50 mM, pH 7.5), and 2 mL was mixed with the same volume of 150 mM cephalosporin C sodium salt. 5 ⁇ The reaction was maintained at a temperature of 7.5. After the start of the reaction, take 100 samples at different times (0, 15, 30, 45 minutes, see Figure 6), mix with 10 ⁇ 3% hydrogen peroxide, add 50 ⁇ 10% trichloroacetic acid, mix to stop the reaction. .
- One unit of D-amino acid oxidase activity is defined as the amount of enzyme which converts one micromoles of cephalosporin C sodium salt to glutaryl-7-aminocephalosporanic acid per minute under the above conditions.
- the total activity of the obtained D-amino acid oxidase mutant GHA was 95,607 units, that is, 35,410 units per liter of fermentation broth.
- Example 13 Preparation of solid phase D-amino acid oxidase mutant GHA
- the D-amino acid oxidase mutant GHA was purified as described in Example 11.
- the preparation of the solid phase D-amino acid oxidase mutant GHA was carried out with reference to the carrier supplier Res indion S. R. L., with specific steps being changed.
- Carrier activation Take 10g of Sepabeads HA wet carrier, add 30mL potassium dihydrogen phosphate buffer (100 mM, pH8), stir at room temperature (300 rpm, 15 minutes), adjust the pH to 8 with 5 N sodium hydroxide. , stand still.
- the vector was filtered, washed with 40 mL of potassium phosphate buffer (20 mM, pH 8) for 5 minutes, filtered and drained.
- the carrier was added to a 40 niL 2% glutaraldehyde solution, stirred at room temperature (300 rpm, 60 minutes), and allowed to stand.
- the vector was filtered, washed with 40 mL of potassium phosphate buffer (20 m M, pH 8) for 5 minutes with stirring, filtered and dried. This washing step was repeated 5 times to activate the wet carrier.
- Enzyme immobilization Proportionally mix activated wet carrier and purified D-amino acid oxidase mutant GHA (100 mL purified D-amino acid oxidase mutant GHA per 10 g of activated wet carrier) and stirred at room temperature (300 rpm, After 1 minute), adjust the pH to 8 with 1N sodium hydroxide, stir for another 18 hours, and let stand.
- the carrier was filtered, and the solid phase product was washed with 40 mL of potassium phosphate buffer (20 mM, pH 8) for 2 minutes with stirring.
- the solid phase product was washed with 40 mL of a sodium chloride solution (0.5 M sodium chloride dissolved in 20 mM potassium phosphate buffer, pH 8) for 20 minutes with stirring.
- Example 14 Fermentation medium and fermentation process of Pseudomonas SE83 glutaryl -7-aminocephalosporanic acid acylase
- Single colony E. coli BL-T7K-ACY was picked from kanamycin (50 g/mL) LB agar plates and inoculated into 2 X 5 mL of kanamycin (50 g/mL). Liquid LB medium, incubated at 37 ° C for 8 hours (shake speed of 250 rpm), Re-inoculate to 2X50 mL seed medium containing kanamycin (50 g/mL) and incubate at 30 ° C for 16 hours (shake speed 400 rpm).
- the weights of the ingredients in the 50 mL seed medium are as follows:
- the ingredients were dissolved in 50 mL of distilled water and sterilized at a high temperature.
- the weight of each component in the 2L fermentation medium is as follows:
- the ingredients were dissolved in 2 L of distilled water and sterilized in a 2 L fermenter (BIOENGINEERING, Benchtop Fermentor, KLF2000).
- the sterilized magnesium sulfate and zinc chloride were placed in a 2 L fermentor before fermentation.
- the barium sulfate was added to the feed, kanamycin was added to a final concentration of 50 g/mL, and 2 mL of defoamer was placed.
- Example 15 Purification of Pseudomonas SE83 glutaryl-7-aminocephalosporanic acid acylase After fermentation according to Example 14, the bacteria were separated by centrifugation at 4 C (5,000 g, 8 minutes), discarded To clear the solution, obtain 130 g of bacteria (wet weight) and resuspend the bacteria in 400 mL of sodium phosphate buffer (50 mM, pH 8). The bacteria were lysed by bead milling, and the bacterial resuspension was sent to a bead mill (DYNO MILL TYP KDL, 0.2 mm diameter glass beads, WA Bachofen) at a rate of 50 mL per minute, and finally 600 mL of sodium phosphate buffer.
- DYNO MILL TYP KDL, 0.2 mm diameter glass beads, WA Bachofen DYNO MILL TYP KDL, 0.2 mm diameter glass beads, WA Bachofen
- the method is basically as described in Binder, R. et al., 1994, Appl. Environ. Microbiol. 60, 1805-1809, wherein the specific steps are changed.
- the Pseudomonas SE83 glutaryl 7-aminocephalosporin acylase extracted as in Example 15 was diluted 10-fold with sodium phosphate buffer (50 mM, pH 8) to the same volume of 150 mM glutaryl- 7-Amino-headed mycophenolic acid (for preparation, see Sh ibuya, Y. et al., 1981, Agri c. Bi ol. Chem. 45, 1561-1567). Mix, react at 37 ° C, keep stirring during the reaction.
- One unit of glutaryl-7-aminocephalosporin acylase activity is defined as the amount of enzyme that converts one micromole of glutaryl-7-aminocephalosporanic acid to 7-aminocephalosporanic acid per minute under the above conditions. .
- Pseudomonas SE83 glutaryl-7-aminocephalosporanic acid acylase was prepared as described in Example 15. The preparation of the solid phase Pseudomonas SE83 glutaryl-7-aminocephalosporanic acid acylase was carried out with reference to the carrier supplier RShm, Germany, with specific steps being changed. 10 g of Eupergit C250L wet carrier was mixed with 100 mL of Pseudomonas SE83 glutaryl-7-aminocephalosporin acylase, stirred at room temperature (300 rpm, 72 hours), and allowed to stand.
- the 1 L 75 mM cephalosporin C sodium salt aqueous solution was added, and 40 g of the solid phase D-amino acid oxidase mutant GHA prepared in Example 13 was added and stirred at room temperature (250 rpm, oxygen supply amount was 0.3 m3 per hour) 1 5 ⁇
- the pH was adjusted to 7.5 by using 3M ammonia (N 0H).
- the reaction solution was filtered, and 50 g of the solid phase Pseudomonas SE83 glutaryl-7-aminocephalosporanic acid acylase prepared in Example 17 was added, stirred at room temperature (250 rpm) for 1 hour, and adjusted with 3 M ammonia water.
- the pH is 8.
- the reaction product, 7-aminocephalosporanic acid was detected by HPLC, and the conditions were the same as those in Example 16.
- the HPLC spectrum is shown in Figure 9. As shown in Figure 9, the entire conversion process was 120 minutes. After 60 minutes from the start of the reaction, most of the cephalosporin C was converted to glutaryl-7-aminocephalosporanic acid by the D-amino acid oxidase mutant GHA ( See Figure 9, GL-7-ACA, 60 min peak). After the reaction was continued for 60 minutes, most of the glutaryl-7-aminocephalosporanic acid was converted to 7-aminocephalosporanic acid by Pseudomonas SE83 glutaryl-7-aminocephalosporin acylase.
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Description
一种用于制备 7-氨基头孢霉垸酸的两步酶法 技术领域
本发明涉及生物工程技术领域, 具体而言涉及一种用于制备 7-氨 基头孢霉烷酸 ( 7-aminocephalosporanic acid ) 的两步酶法。 背景技术
半合成头孢菌素母核 7-氨基头孢霉烷酸可由化学法从头孢菌素 C ( cephalosporin C ) 制备而得。 但是化学法需使用大量有毒制剂, 污染环境, 而且产率低、 成本高。 应用酶法制备精细化学品为近年来 的新兴工艺, 它避免使用有毒制剂, 并且产率较高。 酶法制备 7-氨 基头孢霉烷酸包括两个步骤 (见图 1 ) : ( 1 ) D-氨基酸氧化酶氧化 头 孢 菌 素 C 生 成 戊 二 酰 - 7- 氨 基 头 孢 霉 垸 酸 ( glutaryl-7-aminocephalosporanic acid ) ; ( 2 ) 戊二酰 -7 -氨 基头孢霉烷酸酰化酶水解戊二酰- 7-氨基头孢霉烷酸产生 7-氨基头 孢霉烷酸。
目前限制大规模酶法制备 7-氨基头孢霉烷酸的因素之一为 D-氨 基酸氧化酶和戊二酰 -7-氨基头孢霉烷酸酰化酶的产率低、 成本高。 目前报导的 D-氨基酸氧化酶表达水平较低 (Pol l egioni, L. et al . , 1997, J. Biotechnol. 58, 115-123 : 800酶单位每升发酵液; Molla, G. et al . , 1998, Protein Exp. Purif. 14, 289-294 : 2, 300酶单 位每升发酵液) 。 目前报导的戊二酰 -7-氨基头孢霉烷酸酰化酶表达 7j平也低 ( Ishiye, M.和 Niwa, M., 1992, Biochim. Biophys. Acta 1132, 233-239 : 129 酶单位每升发酵液; 杨蕴刘等, 2001, 中国专 利申请公开号 CN 1301813A : 253 酶单位每升发酵液; 许岗和朱敏, 2003, 中国专利申请公开号 CN 1428424A : 2, 500酶单位每升发酵液)。 因此, 低成本、 大量制备该两个酶是工业化生产 7-氨基头孢霉烷酸 之关键。
目前限制大规模酶法制备 7-氨基头孢霉烷酸的另一因素在于现 有的操作工艺复杂, 成本较高。 例如, 目前工业界使用的 Roche
Diagnostics 公司所生产的有关产品及其工艺 ( CC2 Twin Enzyme Process: D-A0D, 产品号: 1462865; Gl- Ac, 产品号: 1464213, Roche Diagnostics ) 操作步骤较复杂 (见图 1 ) ; 除上述的氧化酶和酰化酶 夕卜, 尚需下列额外步骤: (1 ) 由于 Roche Diagnostics公司之 D-氨基 酸氧化酶不纯,故在氧化反应结束后,仍有较大量 α -酮己二酸单酰 -7- 氨基头孢霉垸酸 ( a - ketoadipyl- 7- ACA) 不能转成戊二酰- 7-氨基头 孢霉烷酸, 因此需外加过氧化氢将之转化成戊二酰 -7-氨基头抱霉烷 酸; (2 ) 但由于过氧化氢一方面会使酶活性丧失, 另方面会氧化头孢 菌素 C和戊二酰- 7-氨基头孢霉烷酸,令最终 7-氨基头孢霉垸酸的产率 降低, 所以需再外加过氧化氢酶去降解残留之过氧化氢。
此外, 中国专利申请公开号为 CN1104255 的专利文献也公开了 一种制备 7-氨基头孢霉垸酸的方法, 在该现有技术的方法中, 因使 用了含氨苄青霉素抗性基因的表达载体, 其发酵产物含 β -内酰胺 酶, 会大大降低 7-氨基头孢霉烷酸的产率, 因此还需在制备 7-氨基 头孢霉烷酸的过程中添加 β -内酰胺酶抑制剂; 并且, 其所使用的细 胞体系还产生能分解过氧化氢的过氧化氢酶,因此在制备过程中不仅 要加入过氧化氢还要加入过氧化氢酶抑制剂。这些使得其操作步骤较 复杂、 成本较高。 发明内容
本发明的目的在于提供一种步骤简单、 成本低、 产率高的用于 制备 7-氨基头孢霉烷酸的两步酶法。
为实现上述目的, 本发明的技术方案提供了一种从头孢菌素 C制 备 7-氨基头孢霉烷酸的方法, 包括用 D-氨基酸氧化酶催化头孢菌素 C 至戊二酰- 7-氨基头孢霉烷酸的第一步反应和用戊二酰 -7-氨基头 孢霉垸酸酰化酶催化戊二酰 -7-氨基头孢霉烷酸至 7-氨基头孢霉烷 酸的第二步反应, 其特征在于, 所述 D-氨基酸氧化酶为经纯化的、 具有序列号 2所示氨基酸序列的三角酵母(Trigonopsis variabilis ) D-氨基酸氧化酶突变体。
在上述技术方案中, 优选的是, 在所述第一步反应中不添加过
氧化氢, 进一步优选的是, 所述 D-氨棊酸氧化酶是由具有序列号 3 所示 DNA序列的表达载体 pHS- GHA表达的, D-氨基酸氧化酶的纯化步 骤包括依次通过 DEAE-纤维素离子交换树脂纯化以及通过硫酸铵沉 淀纯化。 更优选的是, 在所述第一步反应和第二步反应中, 不添加选 自抗坏血酸、 3-氨基- 1, 2, 3-***、过硼酸钠和叠氮化钠的 β -内酰胺 酶抑制剂, 在所述第一步反应中不添加选自舒巴坦钠、 棒酸、 硼酸及 其衍生物的过氧化氢酶抑制剂,在所述第二步反应中不添加过氧化氢 酶。
优选的是, 所述 D-氨基酸氧化酶是固相化的, 或所述戊二酰- 7- 氨基头孢霉烷酸酰化酶是固相化的, 或者 D-氨基酸氧化酶和戊二酰 - 7 -氨基头孢霉烷酸酰化酶都是固相化的。
更优选的是, 所述戊二酰- 7-氨基头孢霉烷酸酰化酶为假单孢菌 ( Pseudomonas sp. ) SE83 戊二酰 -7-氨基头孢霉烷酸酰化酶, 所述 假单孢菌 SE83 戊二酰 -7-氨基头孢霉烷酸酰化酶是由具有序列号 4 所示 DNA序列的表达载体 pT7- kan- ACY表达的
本发明的优点在于: (1 ) 本发明方法中的经纯化的、 具有序列 号 2所示氨基酸序列的三角酵母 ( Trigonopsis variabi lis ) D-氨基 酸氧化酶突变体, 其比活比亲本 D-氨基酸氧化酶高 105%; ( 2 )本发 明方法中的大肠杆菌载体 pHS- GHA和 pT7- kan- ACY, 其发酵产物中不 含有 β -内酰胺酶, 因而不需外加 β -内酰胺酶抑制剂, 减低了生产成 本和简化了工序; (3 ) 本发明方法中的!) -氨基酸氧化酶几乎不含过 氧化氢酶, 因此不需外加过氧化氢酶抑制剂, 并且在反应过程中 α - 酮己二酸单酰 -7-氨基头孢霉烷酸的生成量很低, 因而不需外加过氧 化氢和过氧化氢酶, 减低了生产成本和简化了工序; (4) 使用本发 明的两步固相酶法转化头抱菌素 C至 7-氨基头孢霉烷酸, 克分子转 化率可达 93%以上, 较 Roche Diagnostics公司之产品(克分子转化 率为 82%)髙约 12%。
附图说明
图 1为现行头孢菌素 C转化成 7-氨基头孢霉烷酸的反应流程。
图 2为表达载体 pHS- GHA。
图 3为表达载体 pT7- kan- ACY。
图 4为表达载体 pRSET- lac- GI- hok/sok- kan。
图 5为 D-氨基酸氧化酶突变体 GHA的 SDS- PAGE电泳图。 其中, 1 代表: 蛋白质分子量标记 (BenchMark™ Pre-Stained Protein Ladder (Invitrogen) ) , 单位是 KDa; 2代表: 粗纯 D-氨基酸氧化 酶突变体 GHA; 3代表: 纯化的 D-氨基酸氧化酶突变体 GHA。
图 6为 D-氨基酸氧化酶突变体 GHA转化头孢菌素 C至戊二酰- 7- 氨基头孢霉烷酸的 HPLC图谱。
图 7 为假单孢菌 SE83 戊二酰 -7-氨基头孢霉烷酸酰化酶的 SDS- PAGE电泳图。 其中, 1代表: 蛋白质分子量标记 (BenchMark™ Pre-Stained Protein Ladder (Invitrogen) ) , 单位是 KDa; 2代表: 粗纯假单孢菌 SE83戊二酰 -7-氨基头孢霉烷酸酰化酶。
图 8为假单孢菌 SE83戊二酰 -7-氨基头孢霉烷酸酰化酶转化戊 二酰- 7-氨基头孢霉烷酸至 7-氨基头孢霉烷酸的 HPLC图谱。
图 9为两步固相酶转化头孢菌素 C至 7-氨基头抱霉烷酸的 HPLC 图谱。 具体实施方式
实施例 1 : 表达载体 pRSET- kan的构建
根据 pRSET-A (可购自 Invitrogen) 的序列设计 PCR引物, 具 体为:
上游弓 I物 VET- F: 5, - CTGTCAGACCAAGTTTACTCATATATACTTTAG - 3, ; 下游弓 I物 VET- R: 5, - ACTCTTCCTTTTTCAATATTATTGAAGC-3, 0
根据 pET28b (可购自 Novagen) 的序列设计 PCR引物, 具体为 上游引物 KAN - F: 5, - ATGAGCCATATTCAACGGGAAAC- 3, ;
下游引物 KAN- R: 5, -TTAGAAAAACTCATCGAGCATCAAATG-3 ' 。
扩增去除氨苄青霉素抗性基因的 pRSET- A片段的 PCR条件为: 50 ng pRSET-A ( Invitrogen) , 0. 4 μΜ VET-F, 0. 4 μΜ VET-R, 50 μΜ dATP, 50 μΜ dTTP, 50 μΜ dCTP, 50 μΜ dGTP, 20 mM Tris-HCl ( pH 8. 8 ) , 10 mM KC1 , 10 mM (NH4) 2S04, 2 mM MgS04, 0. 1% Triton X— 100,
2.5U Pfu DNA 聚合酶 (Promega) , 用无菌水调反应体积至 50 μί。
PCR扩增反应程序为: 94°C, 5分钟; 94°C, 1分钟, 5Q°C, 1分钟, 72°C, 4分钟, 循环 35次; 72° C, 10分钟。
扩增卡那霉素抗性基因的 PCR条件为: 50 ng pET28b(Novagen), 0.4 μΜ KAN-F, 0.4 μΜ KAN-R, 50 μΜ dATP, 50 μΜ dTTP, 50 μΜ dCTP, 50 μΜάθΤΡ, 20 mM Tris~HCl (pH8.8) , 10mMKCl, 10 mM (NH4) 2S04, 2 mM MgS04, 0.1% Triton X- 100, 2.5 U Pfu DNA聚合酶 (Promega) , 用无菌水调反应体积至 50 L。 PCR扩增反应程序为: 94° C, 5分钟; 94° C, 1分钟, 50° (, 1分钟, 72° C, 4分钟, 循环 35次; 72° C, 10 分钟。
用 0.8%琼脂糖电泳提纯 PCR产物 (去除氨苄青霉素抗性基因的 pRSET- A片段的 PCR产物长 2, 036 bp; 卡那霉素抗性基因的 PCR产物 长 816 bp) , 连接该两片段得 pRSET- kan。 将 pRSET- kan转化感受态 大肠杆菌 BL21(DE3)pLysS (Novagen) , 在卡那霉素 (50 g/mL) LB
(1%氯化钠, 1%蛋白胨, 0.5%酵母浸膏) 平板上于 37°C培养过夜。 按照 Molecular Cloning- A .Laboratory Manual ( Sambrook, J. et al., 1989, CSHL Press) 描述的方法提取质粒。 实施例 2: 载体 pRSET-lac- kan的构建
根据 pGEMT- Easy (Promega)的序列设计 PCR引物, 具体为: 上游引物 RBS- Ndel: 5, - CATATGTATATCTCCTTCTTGTGTGAAATTG-3,
(Ndel 酶切位点以下划线表示, 外加的核蛋白体结合位点以下间虚线 表示) ;
下游引物 RBS- Al wNI: 5 ' -CAGTGGCTGCTGCCAGTGGCGATAAGTC-3,
(AlwNI酶切位点以下划线表示) 。
以 pGEMT- Easy (Promega)为模板, 用上述引物进行 PCR, 扩增得到 一 755bp 产物。 PCR 条件为: 50 ng pGEMT- Easy (Promega), 0.4 μΜ RBS- Ndel, 0.4 μΜ RBS-AlwNI, 50 μΜ dATP, 50 μΜ dTTP, 50 μΜ dCTP, 50 μΜ dGTP, 20 mM Tris- HC1 (pH 8.8), 10 mM KC1, 10 mM (腿 4)2S04, 2 mM MgS04, 0.1% Triton X - 100, 2.5 U Pfu DNA聚合酶(Promega), 用无菌水调反应体积至 50 μΙα PCR扩增反应程序为: 94°C, 5分钟; 94°C,
1分钟, 50 , 1分钟, 72°C, 4分钟, 循环 35次; Ί2Χ, 10分钟。 该 PCR产物(755bp)在 5' 端含有 Ndel酶切位点和核蛋白体结合位 点及在 3' 端含有 AlwNI酶切位点。 用 0.8%琼脂糖电泳提纯, Ndel和 AlwNI酶切后, 与经 Ndel和 AlwNI酶切的 pRSETA(Invitrogen)连接, 得 pRSET- lac 。 将 pRSET-lac 转 化 感 受 态 大 肠 杆 菌 BL21(DE3)pLysS(Novagen), 在氨苄青霉素(100 g/mL) LB (1%氯化钠, 1°/。蛋白胨, 0.5%酵母浸膏)平板上于 37°C 培养过夜。 按照 Molecular Cloning - A Laboratory Manual (Sambrook, J. et al., 1989, CSHL Press)描述的方法提取质粒。
用 AlwNI和 EcoRI酶切 pRSET- lac和 pRSET- kan,用 0.8%琼脂糖电 泳提纯各 DNA片段并连接, 得 pRSET- lac- kan。 将 pRSET- lac- kan转化 感受态大肠杆菌 BL21(DE3)pLysS(Novagen), 在卡那霉素(50 g/mL) LB 琼脂平板上于 37°C培养过夜。 按照 Molecular Cloning- A Laboratory Manual (Sambrook, J. et al., 1989, CSHL Press)描述的方法提取质 粒。 实施例 3: 载体 pGEMT- Easy- GI的构建
根据已知的 Thermoanaerobac terium sa c charoly ticum glucose isomerase DNA序列(GenBank L09699) , 设计 PGR引物, 具体为: 上游引物(GI- Ndel):
5, -CATATGAATAAATATTTTGAGAACGTATCTAAAATA-3 ,
(Ndel酶切位点以下划线表示) ;
下游引物(GI- EcoRI): 5, - GATATCTTAAGGCGCGCCTTATTCTGCAAAC- 3,
(EcoRI酶切位点以下划线表示, Ascl酶切位点以双下划线表示) 。
以 Thermoanaerobac terium saccharoly ticum (贝勾自 ATCC, USA) DNA为模板, 用上述引物进行 PCR, 扩增得到一 1, 336bp产物。 PCR条 件为: 50 ng T. saccharolyticumM , 0.4 μΜ GI— Ndel, 0.4 μΜ GI - EcoRI, 50 μΜ dATP, 50 μΜ dTTP, 50 μΜ dCTP, 50 μΜ dGTP, 20 mM Tris- HC1 (pH8.8), lOmMKCl, 10 mM (NH4) 2S04, 2mMMgS04, 0.1% Triton X-100, 2.5 U Platinum Taq High Fidelity DNA 聚合酶(Invitrogen), 用无 菌水调反应体积至 50 PCR扩增反应程序为: 95°C, 5分钟; 94°C,
1分钟, 50°C, 1分钟, 72°C, 3分钟, 循环 35次; 72°C, 10分钟。 该 PCR产物(l,336bp)在 5' 和 3' 端分别含有 Ndel和 EcoRI酶切 位点。 PCR 产物经 0.8%琼脂糖电泳提纯, 利用 TA 克隆方法, 与 pGEMT-Easy(Promega)连接, 得 pGEMT- Easy- GI。 将 pGEMT- Easy- GI转 化感受态大肠杆菌 DH5a (Invitrogen) , 在氨苄青霉素(100 ^g/ml) LB 琼脂平板上于 37°C培养过夜。 按照 Molecular Cloning- A Laboratory Manual (Sambrook, J. et al., 1989, CSHL Press)描述的方法提取质粒。 实施例 4: 载体 pRSET- lac- GI- hok/sok- kan (见图 4) 的构建
用 Ndel和 EcoRI酶切 pGEMT- Easy- GI, 经 0.8%琼脂糖电泳提纯, 与经 Ndel和 EcoRI酶切的 pRSET- lac- kan连接,得 pRSET- lac- GI- kan。 将 pRSET- lac- GI- kan转化感受态大肠杆菌 BL21 (DE3) pLysS (Novagen), 在卡那霉素(50 g/mL) LB琼脂平板上于 37°C培养过夜。按照 Molecular Cloning - A Laboratory Manual (Sambrook, J. et al., 1989, CSHL Press)描述的方法提取质粒。
根据已知 hok/sok基因片段序列(GenBank X05813)设计 10条引物 (见表 1)。 PCR 基因构造根据 Kikuchi, M. et al. , 1999, Gene 236:159- 167所述, 唯具体步骤有变更。 PCR条件为: 20 ng各个引物, 50 Μ dATP, 50 μΜ dTTP, 50 瘦 dCTP, 50 Μ dGTP, 20 mM Tris-HCl (pH 8.8) , lOmMKCl, lOmM (N¾)2S04, 2mMMgS04, 0.1% Triton X-100, 2.5U Pfu DNA聚合酶(Promega), 用无菌水调反应体积至 50 μί。
PCR扩增反应程序为: 95°C, 4分钟; 94°C, 1.5 分钟, 50°C, 1.5 分钟, 72。C, 5分钟, 循环 30次; 72°C, 10分钟, 得一 PCR产物长 580 bp,在其 5' 和 3, 端分别含有 Ascl及 EcoRI酶切位点。 PCR产物经 0.8% 琼脂糖电泳提纯, Ascl及 EcoRI酶切后, 与经 Ascl及 EcoRI 酶切的 pRSET-lac-GI-kan 连 接 , 得 pRSET- lac- GI- hok/s。k- kan 。 将 pRSET- lac- GI- hok/sok- kan 转 化 感 受 态 大 肠 杆 菌 BL21 (DE3) pLysS (Novagen) , 在卡那霉素(50 g/mL) LB 琼脂平板上于 37°C 培养过夜。 按照 Molecular Cloning - A Laboratory Manual (Sambrook, J. et al., 1989, CSHL Press)描述的方法提取质粒, 测 定其 DNA序列如序列号 7所示。 其中数个核苷酸有改动: 1368(C -〉 G);
1513 (缺失了 T); 1804 (A->T); 1826 (C->T); 2479 (G->T); 2555 (T -〉 A); 3860 (C->T)。 表 1
实施例 5: 含有 D-氨基酸氧化酶基因重组质粒 pRSET- A-DAO的构建 根据已知三角酵母 D-氨基酸氧化酶基因 5' 和 3' 端序列 (Gonzalez, F. J. , Montes, J. , Martin, F., Lopez, M. C., Ferminan
E., Catalan, J. , Galan, M. A. Dominguez, A. Molecular cloning of TvDAOl, a gene encoding a D - amino acid oxidase from
Trigonopsis variabilis and its expression in Sa c ch aromyc es cerevisiae and Kluyveromyces lac t is. Yeast 13: 1399-1408;
1997) 设计引物如下:
5' - Ndel (引入 Ndel 酶切位点) :
5' -TAGGGCTGACATATGGCTAAAATCGTTGTTATTGGTGC-3-' ;
3, -Bglll (引入 Bglll酶切位点) :
5' - TAGGGCTGAAGATCTCTAAAGGTTTGGACGAGTAAGAGC - 3, 。
以质粒 PJL (杨藴刘等, 中国专利申请公开号: CN 1371999A) 为模板, 用以上两个引物, 在 PfuDNA聚合酶 (Promega) 的作用下, 合成三角酵母 D-氨基酸氧化酶基因。 pJL携带有三角酵母 FA10 D-氨 基酸氧化酶基因 ( Li, W. et al. , Acta Microbiologica Sinica 31:251-253, 1991) 0 PCR反应条件为: 40 ng pJL, 0.4 μΜ 5, -Ndel, 0.4 μΜ 3' -Bglll, 50 μΜ dATP, 50 μΜ dTTP, 50 Μ dCTP, 50 Μ dGTP, 20 mM Tris-HCl (pH 8.8) , 10 mM KC1, 10 mM (NH4) 2S04, 2 mM MgS04, 0.1% Triton X- 100, 2.5 U Pfu DNA 聚合酶, 用无菌水调反应体积 至 50 μΐ。 PCR扩增反应程序为: 94°C, 5分钟; 94°C, 1分钟, 50°C, 1分钟, 72°C, 2分钟, 循环 10次; 94°C, 1分钟, 60°C, 1分钟, 72° C, 2分钟, 循环 25次; 72°C, 10分钟。
得 1,098 bp长 PCR产物,其 5' 和 3, 端分别具有 Ndel和 Bglll 限制性酶切位点。 PCR产物经 1%琼脂糖电泳提纯, Ndel及 Bglll酶 切后, 与经 Ndel 及 Bglll 酶切质粒 pRSET- A (Invitrogen) 得到 的 2.9 Kb 的片段连接, 得连接产物 pRSET- A- DA0。 将 pRSET- A- DAO 转化感受态大肠杆菌 BL21(DE3)pLysS (Novagen) , 在氨苄青霉素 LB平板上 37°C培养,按照 Molecular Cloning- A Laboratory Manual, ed. By J. Sambrook, et. al. , 1989, CSHL Press) 描述的方法提 取质粒, 经 DNA测序, 确定三角酵母 D-氨基酸氧化酶基因 DNA序列 如序列号 5所示,其推测出的氨基酸序列如序列号 6所示。
实施例 6: 含有 D-氨基酸氧化酶突变体 GHA的表达载体的构建
D-氨基酸氧化酶突变体 GHA 由定点突变构建。 定点突变技术主 要参考 PCR Protocols (编者: John M. S.Bartlett and David
Stirling. Totowa, N. J.: Humana Press, 2003. ) 一书的描述。
根据实施例 5克隆的三角酵母 D-氨基酸氧化酶基因之序列 (序 列号 5) , 设计引物如下:
引物 A: 5, -TAGGGCTGACATATGGCTAAAATCGTTGTTATTG -3, ;
引物 B: 5, -TAGGGCTGAAGATCTCTAAAGGTTTGGACGAG -3, ;
引物 C1: 5' -GCAGGTGCCAACTGGCTCCCGTTTTACGATGGAGGCAAG-3' ; 引物 D: 5, -GAGCCAGTTGGCACCTGCCCAAGG-3 ' 。
引物 A和 B是一对外引物。 引物 A包含 Ndel酶切位点, 并有部 份碱基与 D-氨基酸氧化酶基因 5' 端序列交迭; 引物 B包含 Bglll 酶切位点, 并有部份碱基与 D-氨基酸氧化酶基因 3' 端序列交迭。引 物 C1和 D是内引物。 引物 C1将亲本 D-氨基酸氧化酶基因 53位之苏 氨酸转变成脯氨酸。 引物 D部分碱基与引物 C1的序列交迭。
利用聚合酶链式反应, 以 pRSET- A- DA0 为模板, 用引物对 A和 D扩增模板片段 1; 用引物对 B和 C1扩增模板片段 2。 扩增反应条件 为: 20 ng pRSET-A-DAO, 20 mM Tris - HC1 (pH 8.8) , 10 mM KC1, 10 mM (NH4)2S04, 2 mM MgS04, 0.1% Triton X— 100, 0.4 μΜ 引物 A 和 0.4 μΜ 引物 D (扩增模板片段 1) 或 0.4 μΜ 引物 Β和 0.4 μΜ 引 物 C1 (扩增模板片段 2) , 50 μΜ dATP, 50 μΜ dTTP, 50 μΜ dCTP, 50 μΜ dGTP, 1.5 U Pfu DNA聚合酶, 用无菌水调反应体积至 50 μ1。 聚合酶链式反应扩增程序为: 94°C, 2分钟; 94°C, 1分钟, 53°C, 1 分钟, 72°C, 1分钟, 循环 30次; 72°C, 10分钟。
扩增得到的模板片段 1和模板片段 2, 经 1%琼脂糖凝胶电泳分 离纯化后,用以扩增全长基因。扩增全长基因的反应条件为: 20ng模 板片段 1, 20 ng模板片段 2, 20mMTris-HCl (pH 8.8) , lOmMKCl, 10 mM (匪 4)2S04, 2 mM MgS04, 0.1% Triton X- 100, 0.4 μΜ 引物 A 和 0.4 μΜ引物 Β, 50 μΜ dATP, 50 μΜ dTTP, 50 μΜ dCTP, 50 μΜ dGTP, 1.5 U Pfu DNA 聚合酶, 用无菌水调反应体积至 50 μ1。 聚合酶链式
反应扩增程序为: 94° C, 2分钟; 94° C, 1分钟, 53° C, 1分钟, 72° C, 2分钟, 循环 35次; 72° C, 10分钟。
全长扩增反应得到 D-氨基酸氧化酶突变体 GHA 基因, 经 Ndel 及 Bglll酶切后连接到 pRSET- kan得连接产物 pRSET- kan- DA0GHA, 将 pRSET-kan- DA0GHA转化感受态大肠杆菌 BL21 (DE3) pLysS , 卡那霉 素 LB平板 37° C培养, 提取质粒, 经 DNA测序确定引入的突变无误, 确定 D-氨基酸氧化酶突变体 GHA的 DNA序列如序列号 1所示,其推测 出的氨基酸序列如序列 2所示。 实施例 7: 载体 pHS- GHA (见图 2) 的构建
用 Ndel和 Bgl ll酶切质粒 RSET-kan-DAOGHA,得一 1, 074bp基 因片段 (内含 D-氨基酸氧化酶突变体 GHA基因) , 经 0. 8%琼脂糖电 泳提纯, 与经 Ndel和 Bgl ll酶切的 pRSET- lac- GI- hok/sok- kan得到 的长片断连接, 得 pHS- GHA。 将 pHS- GHA 转化感受态大肠杆菌 BL21 (DE3) pLysS ( Novagen) , 得菌株 BL- HS- GHA, 在卡那霉素 (50 g/mL ) LB琼脂平板上于 37° C培养过夜。按照 Molecular Cloning- A Laboratory Manual ( Sambrook, J. et al., 1989, CSHL Press ) 描述的方法提取质粒, 测定其 DNA序列如序列号 3所示。 其中数个核 苷酸有改动: 1390 (d) ; 1535 (缺失了 T) ; 1826 (A->T) ; 1848 (C->T); 2501 (G->T); 2577 (T->A); 3882 (C -〉 T)。 实施例 8 : 载体 pT7- kan-ACY (见图 3 ) 的构建
根据已知的假单孢菌 SE83 戊二酰 -7-氨基头孢霉烷酸酰化酶 DNA 序列 ( Matsuda, A. et al., 1987, J. Bacteriol. 169, 5821-5826 ) , 设计 PCR引物如下:
上游引物(Ndel- ACY): 5, -CATATGAACGCTCCCGTCCCCGTCCC-3 ' , Ndel 酶切位点以下划线表示;
下游引物 (Bglll- ACY) : 5, -AGATCTTCAGATGGTGAAGCGGGCAC-3, , Bglll酶切位点以下划线表示。
以假单孢菌 SE83 DNA为模板, 用上述引物进行 PCR, 扩增得到
一 1, 676bp产物。 PCR条件为: 50 ng假单孢菌 SE83 DNA, 0.4 μΜ Ndel-ACY, 0.4 μΜ Bglll-ACY, 50 μΜ dATP, 50 μΜ dTTP, 50 μΜ dCTP, 50 μΜάΰΤΡ, 20 mMTris-HCl (pH8.8) , 10 mMKCl, 10 mM (腿 4) 2S04, 2 mMMgS04, 0· 1% Triton X- 100, 2.5 U Pfu DNA聚合酶 (Promega) , 用无菌水调反应体积至 50 μί。
PCR扩增反应程序为: 95°C, 5 分钟; 94°C, 1 分钟, 50°C, 1 分钟, 72DC, 3分钟, 循环 35次; 72° (:, 10分钟。
该 PCR产物 (l,676bp) 在 5' 和: T 端分别含有 Ndel和 Bglll 酶切位点。 PCR产物经 0.8%琼脂糖电泳提纯, Ndel和 Bglll酶切后, 与经 del 和 Bglll 酶切的 pRSET-kan连接, 得 pT7- kan- ACY。 将 pT7- kan- ACY转化感受态大肠杆菌 BL21(DE3)pLysS (Novagen) , 得 菌株 BL- T7K- ACY, 在卡那霉素 (50 μg/mL LB 琼脂平板上于 37°C 培养过夜。按照 Molecular Cloning- A Laboratory Manual ( Sambrook, J. et al. , 1989, CSHL Press) 描述的方法提取质粒, 测定其 DNA 序列如序列号 4 所示。 其中四个核苷酸有改动: 2260(G->T) ; 2336 (T->A); 3641 (C_〉T); 4117 (G -〉 C。 实施例 9: D-氨基酸氧化酶突变体 GHA之发酵培养基及发酵工艺
从卡那霉素 (50 H D LB 琼脂平板上挑取单菌落大肠杆菌 BL-HS-GHA (见实施例 7) , 接种到 2X5 mL含卡那霉素 (50 g/mL) 的液体 LB培养基,在 37°C培养 8小时(摇床转速为 250转每分钟), 再接种至 2X50 mL种子培养基含卡那霉素(100 g/mL)和氯霉素(40 H/mL , 在 30°C培养 16小时 (摇床转速为 400转每分钟) 。
玉米浆 1之制备:
将 300 g玉米浆 (购自华北制药康欣有限公司) 溶于 300 mL蒸 馏水, 搅拌后离心 (5,000 g, 8分钟) , 上清液即为玉米浆 1。 沉淀 物留用。
玉米浆 2之制备:
将上述沉淀物再溶于 600 mL蒸馏水, 搅拌后离心 (5, 000 g, 8 分钟) , 上清液即为玉米浆 2。
50 mL种子培养基中各成分重量如下
玉米浆 1 4 mL
玉米浆 2 4 mL
0.2 g
硫酸铵 0.075 g
磷酸氢二钠 0.25 g
磷酸二氢钾 0.04 g
氯化钠 0.075 g
将各成分溶于 50 mL蒸熘水, 以 10 N氢氧化钠调 pH值至 7.15, 高温消毒。
种子过夜发酵后, 将全部 100 mL 之种子接种至 2 L 发酵罐 (BIOENGINEERING, Benchtop Fermentor, KLF2000)含卡那霉素 (50 g/mU 。
2L发酵培养基中各成分重量如下:
玉米浆 1 160 mL
玉米浆 2 160 mL
8 g
硫酸铵 3 g
磷酸氢二钠 10 g
磷酸二氢钾 1 g
氯化钠 3 g
将各成分溶于 1.9 L蒸馏水, 以 10 N氢氧化钠调 pH值至 7.15, 于 2 L发酵罐 (BIOENGINEERING, Benchtop Fermentor, KLF2000) 将 12.5 g葡萄糖溶于 50 mL蒸馏水, 高温消毒; 将 1.25 g硫 酸镁溶于 50 mL蒸馏水, 高温消毒。
发酵前把已消毒的葡萄糖和硫酸镁放进 2 L发酵罐。
补料之制备:
将 250 mL玉米浆 1和 250 mL玉米浆 2混合, 以 10 N氢氧化钠 调 pH值至 7.25, 高温消毒。
将 2.25 g硫酸铵, 7.56 g磷酸氢二钠, 1.2 g磷酸二氢钾, 2.25 g氯化钠溶于 60 mL蒸馏水, 高温消毒。
将 15 g酵母浸膏溶于 100 mL蒸馏水, 高温消毒。
将 70 g葡萄糖溶于 140 mL蒸馏水, 高温消毒。
将 30 mL甘油混合 10 mL蒸馏水, 高温消毒。
将 20 g硫酸镁溶于 30 mL蒸馏水, 高温消毒。
将所有溶液混合, 加入卡那霉素至浓度为 50 μ§ , 加入 2 mL 消泡剂。
在 35°C生长, 在初始的 6小时, pH值由 6.9 自然上升至 7.2, 开始补料 (50 mL/小时) 。 在平衡条件下 (以 5 N氢氧化钾将 pH值 维持在 7.2, 溶氧水平 p02不大于 0.5%) , 继续生长 26小时。 实施例 10: 粗纯 D-氨基酸氧化酶突变体 GHA之提取
按实施例 9发酵后, 细菌在 4°C经离心机分离 (5,000 g, 8分 钟) , 弃上清液, 得 220 g细菌 (湿重) , 将细菌重悬于 600 mL磷 酸钠缓冲液 (50 mM, pH7.5) 。 用珠磨法裂解细菌, 以 50 mL每分钟 之速度把细菌重悬液送进珠磨机 (DYNO- MILL TYP KDL, 0.2 mm直径 玻璃珠, WA Bachofen) 内, 最后再以 800 mL磷酸钠缓冲液 (50 mM, pH7.5) 把细菌残留冲洗出来。 将细菌裂解液放在 55°C 水浴中浸泡 30分钟, 以高速离心 ( 10,000 g, 30分钟) , 取上清液, 即为粗纯 之 D-氨基酸氧化酶突变体 GHA。 取样并采用 SDS- PAGE检测目标蛋白 的纯度和含量 (见图 5) 。 如图所示, 粗纯之 D-氨基酸氧化酶突变体 GHA约占总可溶蛋白 40%。 实施例 11: D-氨基酸氧化酶突变体 GHA之提纯
取按实施例 10提取之粗纯 D-氨基酸氧化酶突变体 GHA, 加入甘 油至最终浓度为 10%, 用 5N氢氧化钠调 pH值至 8, 离心 (13,000 g, 30分钟) , 取上清液。 按产品供应商所述产品制备法配备 DEAE-纤维 素离子交换树脂(Sigma, D-0909)。按每 ImL粗纯酶混合 0.5raL DEAE- 纤维素离子交换树脂, 在 4°C搅拌 5小时 (100转每分钟) , 用滤斗
( Buchner filter funnel , 120 mm PI ) 将酶液滤去。 以 3份 DEAE- 纤维素离子交换树脂体积之 40 mM磷酸二氢钠缓冲液 (含 10%甘油) 冲洗 DEAE-纤维素离子交换树脂, 再用 2份 DEAE-纤维素离子交换树 脂体积之 400 mM磷酸二氢钠缓冲液将 D-氨基酸氧化酶突变体 GHA洗 脱出来。 按每 1L洗脱之 D-氨基酸氧化酶突变体 GHA, 加入 262 g硫 酸铵, 在室温搅拌 15分钟 (100转每分钟) 。 离心 ( 13, 000 g, 15 分钟) , 弃上清液, 保留沉淀物。 将沉淀物溶于 10 mM磷酸二氢钠缓 冲液(pH7. 5 )。取样并采用 SDS- PAGE检测目标蛋白的纯度和含量(见 图 5 ) 。 如图所示, 提取之 D-氨基酸氧化酶突变体 GHA约占总可溶蛋 白 90% 实施例 12 : D-氨基酸氧化酶突变体 GHA活性的检测
检测基本按 Isogai, T, et al. , 1990, J. Biochem. [Tokyo] 108 1063- 1069所述之方法, 其中具体步骤有变更。 将按实施例 11纯化 的 D-氨基酸氧化酶突变体 GHA用磷酸钠缓冲液 (50 mM, pH7. 5 ) 稀 释 10倍, 取 2 mL, 与相同体积之 150 mM头孢菌素 C钠盐混合, 在 37° C下反应, 反应中保持搅拌 (搅拌速度为 450转每分钟) , 并用 5N氢氧化钠将 pH值保持在 7. 5。反应开始后在不同时间(0, 15, 30, 45分钟, 见图 6 ) 抽取 100 样本, 与 10 μΐ 3%过氧化氢混匀, 再 加入 50 μΐ 10%三氯醋酸,混匀以终止反应。离心( 10, 000g, 3分钟), 取 10 μΐ上清液混合 990 μΐ HPLC流动相 (50 mM磷酸钾, pH7 ; 5% 乙腈) 。 用 HPLC检测酶反应, 条件如下:
HPLC色谱柱: Diamonsil™ C18, 250 X 4. 6 mm (迪马公司, 北京) 柱温度: 30° C
流速: 1 raL每分钟
检测: 260 匪
一单位 D-氨基酸氧化酶活性定义为在上述条件每分钟转化一微 摩尔头孢菌素 C钠盐至戊二酰 -7-氨基头孢霉烷酸的酶量。
获得之 D-氨基酸氧化酶突变体 GHA总活性为 95, 607单位,即每 升发酵液含 35, 410单位。
实施例 13 : 固相 D-氨基酸氧化酶突变体 GHA之制备
按实施例 11所述纯化 D-氨基酸氧化酶突变体 GHA。固相 D-氨基 酸氧化酶突变体 GHA之制备参照载体供应商意大利 Res indion S. R. L. 的说明进行, 其中具体步骤有变更。
载体活化: 取 10g Sepabeads HA湿载体, 加入 30 mL磷酸二氢 钾缓冲液 (100 mM, pH8 ) , 在室温下搅拌 (300转, 15分钟) 后, 用 5 N氢氧化钠调 pH值至 8, 静置。 将载体过滤, 用 40 mL磷酸钾 缓冲液 (20 mM, pH8 ) 搅拌洗涤 5分钟, 再过滤并抽干。 将载体加入 40 niL 2%戊二醛溶液, 在室温下搅拌 (300转, 60分钟) , 静置。 将 载体过滤, 用 40 mL磷酸钾缓冲液 (20 mM, pH8 ) 搅拌洗涤 5分钟, 再过滤并抽干。 重复此洗涤步骤 5次, 为活化湿载体。
酶固相化: 按比例混合活化湿载体和纯化 D-氨基酸氧化酶突变 体 GHA (每 10 g活化湿载体混合 100 mL纯化 D-氨基酸氧化酶突变体 GHA ) , 在室温下搅拌 (300 转, 1 分钟) 后, 用 1N氢氧化钠调 pH 值至 8 , 再搅拌 18 小时, 静置。 将载体过滤, 将固相产物用 40 mL 磷酸钾缓冲液 (20 mM, pH8 ) 搅拌洗涤 2分钟, 再过滤。 将固相产物 用 40 mL氯化钠溶液 (0. 5 M氯化钠溶于 20 mM磷酸钾缓冲液, pH8 ) 搅拌洗涤 20分钟, 过滤。 重复此洗涤步骤直至洗涤液中蛋白量少于 0. 1 mg/mL。 将固相产物用 40 mL磷酸钾缓冲液 (20 mM, pH8 ) 搅拌 洗涤 2分钟, 过滤及抽干后, 得 115 g固相 D-氨基酸氧化酶突变体 GHA。 固相酶活性之检测基本上与实施例 12所述相同, 其中所用反应 液体积为 200 mL的 75 mM头孢菌素 C钠盐, 加入 4g固相 D-氨基酸 氧化酶突变体 GHA, 测得活性为 77单位 /g湿载体。 实施例 14: 假单孢菌 SE83戊二酰 -7-氨基头孢霉烷酸酰化酶的发酵 培养基及发酵工艺
从卡那霉素 (50 g/mL ) LB 琼脂平板上挑取单菌落大肠杆菌 BL-T7K-ACY (见实施例 8 ) , 接种到 2 X 5mL含卡那霉素 (50 g/mL) 的液体 LB培养基,在 37° C培养 8小时(摇床转速为 250转每分钟),
再接种至 2X50 mL 种子培养基含卡那霉素 (50 g/mL) , 在 30°C 培养 16小时 (摇床转速为 400转每分钟) 。
50 mL种子培养基中各成分重量如下:
0.35 g
磷酸氢二纳 0.35 g
磷酸二氢钾 0.35 g
磷酸氢二钾 0.48 g
硫酸铵 0.06 g
氯化铵 0.01 g
甘油 0.5 mL
氯化钙 0.00055 g
将各成分溶于 50mL蒸馏水, 高温消毒。
种子过夜发酵后, 将全部 lOOmL 之种子接种至 2L 发酵罐 (BIOENGINEERING, Benchtop Fermentor, KLF2000)含卡那霉素 (50 g/mU 。
2L发酵培养基中各成分重量如下:
14 g
二纳 14 g
磷酸二氢钾 14 g
磷酸氢二钾 19.2 g
硫酸铵 2.4 g
氯化铵 0.4 g
甘油 20 mL
氯化钙 0.022 g
将各成分溶于 2 L蒸熘水, 于 2 L发酵罐 (BIOENGINEERING, Benchtop Fermentor, KLF2000) 高温消毒。
将 1 g硫酸镁溶于 20 mL蒸馏水, 高温消毒; 将 0.14 g氯化锌 溶于 20 mL蒸熘水, 高温消毒。
发酵前把已消毒的硫酸镁和氯化锌放进 2 L发酵罐。
补料之制备:
酵母浸膏 14 g
磷酸氢二纳 4.9 g
磷酸二氢钾 4.9 g
磷酸氢二钾 6.4 g
硫酸铵 0.84 g
氯化铵 0.14 g
甘油 175 mL
氯化钙 0.008 g
将各成分溶于 700 mL蒸馏水, 高温消毒。
将 0.34 g硫酸镁溶于 20 mL蒸馏水, 高温消毒后, 加进已消毒 之 700 mL之补料。
进行补料前, 将硫酸锾加入补料, 加卡那霉素至最终浓度为 50 g/mL, 放入 2 mL消泡剂。
在 30°C生长, 在初始的 4小时内, 以 5 N氢氧化钾将 pH值由 6.9缓慢调升至 7.2。 当 0D6。。值达至 4时, 开始补料 (60mL/小时) 。 在之后的 4小时内再用 5N氢氧化钾将 pH值调升至 7.4。当 0D6。。值达 至 8时, 加入异丙基硫代半乳糖苷 (IPTG, Sigma) 至 0.1 mM。 以 5N 氢氧化钾将 pH值维持在 7.4, 溶氧水平 p02维持在 30%, 继续生长 26 小时。 实施例 15: 假单孢菌 SE83戊二酰 -7-氨基头孢霉烷酸酰化酶之提纯 按实施例 14 发酵后, 细菌在 4 C 经离心机分离 (5,000 g, 8 分钟) , 弃上清液, 得 130 g细菌 (湿重) , 将细菌重悬于 400 mL 磷酸钠缓冲液 (50mM, pH8) 。 用珠磨法裂解细菌, 以 50 mL每分钟 之速度把细菌重悬液送进珠磨机 (DYNO MILL TYP KDL, 0.2 mm直径 玻璃珠, WA Bachofen) 内, 最后再以 600 mL磷酸钠缓冲液 (50 mM, pH8) 把细菌残留冲洗出来。 将细菌裂解液放在 55QC水浴中浸泡 15 分钟, 以高速离心 (10, 000 g, 30 分钟) , 取上清液, 即为粗纯之 假单孢菌 SE83 戊二酰 -7-氨基头孢霉烷酸酰化酶。 取样并采用 SDS- PAGE检测目标蛋白的纯度和含量 (见图 7) 。 如图所示, 粗纯之
假单孢菌 SE83 戊二酰 -7-氨基头孢霉烷酸酰化酶约占总可溶蛋白
实施例 16 : 假单孢菌 SE83戊二酰 -7-氨基头孢霉垸酸酰化酶活性的 检测
检测基本按 Binder, R. et al ., 1994, Appl . Environ. Microbi ol . 60, 1805- 1809 所述之方法, 其中具体步骤有变更。 将 按实施例 15提取的假单孢菌 SE83戊二酰 7-氨基头孢霉垸酸酰化酶 用磷酸钠缓冲液 (50 mM, pH8 ) 稀释 10 倍, 与相同体积之 150 mM 戊二酰 - 7-氨基头抱霉垸酸(制备方法参见 Sh ibuya, Y. et al . , 1981 , Agri c. Bi ol . Chem. 45, 1561-1567 ) 混合, 在 37° C下反应, 反应 中保持搅拌 (搅拌速度为 450转每分钟) , 并用 5 N氢氧化钠将 pH 值保持在 8。 反应开始后在不同时间 (0, 15, 30, 45分钟, 见图 8 ) 抽取 60 L样本,与 30 μΐ 10%三氯醋酸混勾以终止反应。离心( 10, 000 g, 3分钟) , 取 10 μΐ^上清液混合 990 μΐ HPLC流动相 (50 mM磷酸 钾, pH7 ; 5%乙腈) 。 用 HPLC检测酶反应, 条件和实施例 12相同。
一单位戊二酰 -7-氨基头孢霉垸酸酰化酶活性定义为在上述条 件每分钟转化一微摩尔戊二酰- 7-氨基头孢霉烷酸至 7-氨基头孢霉 烷酸的酶量。
获得之假单孢菌 SE83 戊二酰 -7-氨基头孢霉烷酸酰化酶总活性 为 24, 882单位, 即每升发酵液含 9, 570酶单位。 实施例 17 : 固相假单孢菌 SE83戊二酰 -7-氨基头孢霉烷酸酰化酶之 制备
按实施例 15所述制备假单孢菌 SE83戊二酰 -7-氨基头孢霉烷酸 酰化酶。固相假单孢菌 SE83戊二酰 -7-氨基头孢霉烷酸酰化酶之制备 参照载体供应商德国 RShm公司的说明进行, 其中具体步骤有变更。 取 10 g Eupergit C250L湿载体混合 100 mL假单孢菌 SE83戊二酰 -7 - 氨基头孢霉垸酸酰化酶, 在室温下搅拌 (300转, 72小时) , 静置。 过滤, 用 100 mL蒸馏水在室温下搅拌洗涤 (300转, 2分钟) , 用 3
号砂芯漏斗抽干, 重复此洗涤步骤直至过滤液中蛋白量少于 0. 1 mg/mL,得 8Q g固相假单孢菌 SE83戊二酰 -7-氨基头孢霉烷酸酰化酶。 固相酶活性之检测基本上与实施例 16所述相同, 其中所用反应液体 积为 200 mL 75 mM戊二酰 -7-氨基头孢霉垸酸, 加入 6 g固相假单抱 菌 SE83戊二酰 -7-氨基头孢霉烷酸酰化酶, 测得活性为 50单位 /g湿 载体。 实施例 18 : 两步固相酶转化头孢菌素 C至 7-氨基头孢霉烷酸
制备 1L 75mM头孢菌素 C钠盐水溶液, 加入 40g按实施例 13制 备之固相 D-氨基酸氧化酶突变体 GHA, 在室温搅拌 (250转每分钟, 供氧量为 0. 3m3每小时) 1小时, 用 3M氨水(N 0H)调 pH值为 7. 5。 过滤反应液,加入 50g按实施例 17制备之固相假单孢菌 SE83戊二酰 - 7 -氨基头孢霉烷酸酰化酶, 在室温搅拌(250转每分钟) 1小时, 用 3M 氨水调 pH值为 8。 用 HPLC检测反应产物 7-氨基头孢霉烷酸, 条 件和实施例 16相同。 HPLC图谱见图 9。 如图 9所示, 整个转化过程 为 120分钟, 在反应开始 60分钟后, 绝大部分头孢菌素 C被 D-氨基 酸氧化酶突变体 GHA 转化成戊二酰 -7-氨基头孢霉烷酸 (见图 9, GL-7-ACA, 60分钟峰) 。 反应继续进行 60分钟后, 绝大部分戊二酰 -7 -氨基头孢霉烷酸被假单孢菌 SE83戊二酰 -7-氨基头孢霉垸酸酰化 酶转化成 7-氨基头孢霉烷酸 (见图 9 , 7-ACA, 120分钟峰) 。 根据 HPLC数据计算, 由头孢菌素 C转化成戊二酰 -7-氨基头孢霉垸酸之产 率为 97. 96%;由戊二酰- 7-氨基头孢霉烷酸转化成 7-氨基头孢霉烷酸 之产率为 95. 78% 由头孢菌素 C经两步酶法转化成 7-氨基头孢霉烷 酸之总产率为 93. 83%。 本发明不受上述具体文字描述的限制。 本发明可在权利要求书 所概括的范围内做各种改变, 这些改变均在本发明的范围之内。
Claims
1. 一种从头孢菌素 C 制备 7-氨基头孢霉烷酸的方法, 包括用 D-氨基酸氧化酶催化头孢菌素 C至戊二酰 -7-氨基头孢霉垸酸的第一 步反应和用戊二酰- 7-氨基头抱霉烷酸酰化酶催化戊二酰 -7-氨基头 孢霉烷酸至 7-氨基头孢霉垸酸的第二步反应, 其特征在于, 所述 D - 氨基酸氧化酶为经纯化的、具有序列号 2所示氨基酸序列的三角酵母
( Trigonopsis variabi lis ) D -氨基酸氧化酶突变体。
2. 根据权利要求 1所述的方法, 所述第一步反应中不添加过氧 化氢。
3. 根据权利要求 2所述的方法, 所述 D-氨基酸氧化酶是由具有 序列号 3所示 DNA序列的表达载体 pHS- GHA表达的。
4. 根据权利要求 3所述的方法, 所述 D-氨基酸氧化酶的纯化包 括依次通过 DEAE-纤维素离子交换树脂纯化以及通过硫酸铵沉淀纯 化。
5. 根据权利要求 4所述的方法, 所述第一步反应和第二步反应 都不添加选自抗坏血酸、 3-氨基- 1, 2, 3-***、 过硼酸钠和叠氮化钠 的 β -内酰胺酶抑制剂。
6: 根据权利要求 5所述的方法, 所述第一步反应中不添加选自 舒巴坦钠、 棒酸、 硼酸及其衍生物的过氧化氢酶抑制剂。
7. 根据权利要求 6所述的方法, 所述第二步反应中不添加过氧 化氢酶。
8. 根据权利要求 1-7中任意一项所述的方法, 所述 D-氨基酸氧
化酶是固相化的, 或者所逑戊二酰 -7-氨棊头孢霉烷酸酰化酶是固相 化的。
9. 根据权利要求 8所述的方法, 所述戊二酰- 7-氨基头孢霉烷 酸酰化酶为假单孢菌 (Pseudomonas sp. ) SE83 戊二酰 -7-氨基头孢 霉垸酸酰化酶。
10. 根据权利要求 9所述的方法,所述假单孢菌 SE83戊二酰 -7- 氨基头抱霉烷酸酰化酶是由具有序列号 4所示赚序列的表达载体 pT7- kan- ACY表达的。
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WO2003076640A2 (en) * | 2002-03-12 | 2003-09-18 | Bioferma Murcia, S.A. | A process for the preparation of cephalosporan acid derivatives from cephalosporin c |
CN1680583A (zh) * | 2004-04-08 | 2005-10-12 | 百瑞全球有限公司 | 重组 d-氨基酸氧化酶的用途 |
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WO2003076640A2 (en) * | 2002-03-12 | 2003-09-18 | Bioferma Murcia, S.A. | A process for the preparation of cephalosporan acid derivatives from cephalosporin c |
CN1680583A (zh) * | 2004-04-08 | 2005-10-12 | 百瑞全球有限公司 | 重组 d-氨基酸氧化酶的用途 |
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