WO2023036103A1 - 制备不同分子量肝素的磺酸化修饰体系构建及其应用 - Google Patents

制备不同分子量肝素的磺酸化修饰体系构建及其应用 Download PDF

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WO2023036103A1
WO2023036103A1 PCT/CN2022/117166 CN2022117166W WO2023036103A1 WO 2023036103 A1 WO2023036103 A1 WO 2023036103A1 CN 2022117166 W CN2022117166 W CN 2022117166W WO 2023036103 A1 WO2023036103 A1 WO 2023036103A1
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sulfonate
heparin
heparan
transferase
derived
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French (fr)
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康振
陈坚
王璟
堵国城
孟俊东
张永淋
汤传根
王阳
张腾
李江华
盛靖雨
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江南大学
南京汉欣医药科技有限公司
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    • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
    • C12N9/10—Transferases (2.)
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    • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
    • C12N9/90—Isomerases (5.)
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    • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
    • C12P19/00—Preparation of compounds containing saccharide radicals
    • C12P19/24—Preparation of compounds containing saccharide radicals produced by the action of an isomerase, e.g. fructose
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
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    • C12Y503/00—Intramolecular oxidoreductases (5.3)
    • C12Y503/01—Intramolecular oxidoreductases (5.3) interconverting aldoses and ketoses (5.3.1)
    • C12Y503/01012—Glucuronate isomerase (5.3.1.12)

Definitions

  • the invention relates to the construction and application of a sulfonated modification system for preparing heparins with different molecular weights, and belongs to the field of biomedicine.
  • Heparin is a kind of glycosaminoglycan with multiple biological functions. It is composed of GlcA and GlcNAc linked by ⁇ -1,4 and ⁇ -1,4 glycosidic bonds and modified by allosteric and sulfonated. Almost every type of cell in an animal has the ability to synthesize heparin. Heparin is widely present on the cell surface or in the extracellular matrix in the form of proteoglycans. Heparin interacts with a variety of protein ligands to regulate a range of biological activities, including developmental processes, angiogenesis, blood coagulation, and tumor metastasis.
  • the first step is to use N-deacetylase/N-sulfotransferases (NDST) with two catalytic functions to convert GlcNAc
  • NDST N-deacetylase/N-sulfotransferases
  • the acetyl group is removed to form glucosamine (GlcNAc) containing free amino groups, and then N-sulfotransferase transfers a sulfonic acid group to glucosamine to form GlcNS.
  • the sulfotransferase interacts with the donor of the sulfonic acid group, 3'-phosphate-adenosine-5'-phosphosulfonic acid (3'-phosphoadenosine5/phosphosulfate, PAPS) to transfer the sulfonic acid group to the corresponding sugar unit Location.
  • D-GlcA forms L-IdoA through epimerase (C5-epimerase, C5-epi), followed by 2-sulfotransferases (2-sulfotransferases, 2-OSTs) Transfer of the sulfonic acid group to the C2 position of IdoA or GlcA forms IdoA2S or GlcA2S. Then the C6 and C3 positions of GlcNS are sulfonated by 6-sulfotransferases (6-sulfotransferases, 6-OSTs) and 3-sulfotransferases (3-sulfotransferases, 3-OSTs), respectively.
  • 6-sulfotransferases 6-sulfotransferases
  • 3-sulfotransferases 3-sulfotransferases
  • heparin derived from animal tissue has always faced the problems of unstable structure and complex composition.
  • the Batram incident in 2007-2008 was caused by a certain amount of chondroitin persulfonate mixed in heparin.
  • the synthesis of heparin by microbial enzyme method can effectively avoid the above problems.
  • the present invention uses Pichia pastoris as a platform strain to express heparin-modifying enzymes (NDST1, C5 epi, 2-OST, 6-OST1 and 3-OST1), and prepare heparin-modified enzymes through system optimization. Enzymes to prepare heparin with different sulfonation degrees.
  • the co-culture system of Pichia pastoris is used to prepare heparin with different molecular weights by adding PAPS in vitro and starting from ATP. Because the bio-enzyme method has the advantages of mild reaction conditions, high specificity, and easy control of the product, it is easy to realize industrial production and preparation of heparin.
  • the present invention organically combines multiple catalytic systems to form a method that can efficiently catalyze and synthesize heparin through multi-enzyme cascade reactions.
  • This method can be obtained in two ways: (1) heparin precursor, heparin modifying enzyme and PAPS or (2) heparin precursor, heparin modifying enzyme, PAPS synthetic bifunctional enzyme ASAK S , PPK S , ATP and MgSO 4 react to obtain Ultimate heparin.
  • the method is simple to operate, low in cost and has great practical value.
  • the purpose of the present invention is to overcome the problems in the prior art, realize the directional production of heparin by microbial enzymatic method, overcome various disadvantages brought by the traditional tissue extraction method, and the inefficiency and tediousness of the conventional chemical enzymatic method to catalyze the synthesis of heparin , and greatly reduce the production cost.
  • the purpose of the present invention is to overcome the problems in the prior art, to realize the synthesis of heparin with different molecular weights through the expression of heparin modifying enzymes by Pichia pastoris, and then use methanol as an inducer to induce the expression of heparin modifying enzymes, so as to realize the synthesis of heparin precursors with different molecular weights.
  • the invention provides a method for sulfonating and modifying heparin precursor.
  • the method is to add PAPS and heparin modifying enzyme into the system containing heparin precursor, and the heparin modifying enzyme includes N-deacetyl/N-sulfonate Acid transferase, glucuronate C5-allosterase, heparan sulfonate 2-sulfotransferase, heparan sulfonate 6-sulfotransferase, and heparan sulfonate 3-sulfotransferase.
  • the N-deacetyl/N-sulfonate transferase is derived from Homo sapiens; the glucuronic acid C5-mutosterase is derived from Homo sapiens; the sulfonate heparan 2-sulfonic acid The transferase is derived from Gallus; the sulfonate heparan 6-sulfonate transferase is derived from Gallus; the sulfonate heparan 3-sulfonate transferase is derived from Mus musculus.
  • the Genbank number of the N-deacetyl/N-sulfonate transferase is NM_001543 (the nucleotide sequence is shown in SEQ ID NO.1); the glucuronic acid C5-allosterase The Genbank number of NP_056369.1 (nucleotide sequence as shown in SEQ ID NO.3); 5); the Genbank number of the heparan sulfonate 6-sulfotransferase is NP_989813.1 (the nucleotide sequence is shown in SEQ ID NO.11); the heparan sulfonate 3-sulfonic acid The Genbank number NP_034604.1 of transferase (nucleotide sequence is as shown in SEQ ID NO.17).
  • the heparin-modifying enzyme is added to the reaction system simultaneously or step by step.
  • the stepwise addition is to first add N-deacetyl/N-sulfonate transferase to the reaction system containing heparin precursor and PAPS; after the reaction, add glucuronic acid C5- Mutasterase and heparan sulfonate 2-sulfotransferase were added to the reaction system for reaction; after the reaction, heparan 6-sulfotransferase was added to the reaction system for reaction; after the reaction, acetyl sulfonate was added Heparin 3-sulfonate transferase reaction.
  • PAPS is added in excess compared to heparin precursor, i.e. the molar ratio of heparin precursor to PAPS is greater than 1:1.
  • the invention provides a method for preparing heparins with different molecular weights.
  • the method uses heparin precursors with different molecular weights as substrates, and adds PAPS, N-deacetyl/N-sulfonate transferase, glucuronic acid C5-alterosteric Enzymes, heparan sulfonate 2-sulfonate transferase, heparan sulfonate 6-sulfonate transferase and heparan sulfonate 3-sulfonate transferase, catalyze the production of heparins with different molecular weights;
  • the N-deacetyl/N-sulfonate transferase is derived from Homo sapiens; the glucuronic acid C5-mutosterase is derived from Homo sapiens; the sulfonate heparan 2-sulfonate transferase is derived from Gallus; the The sulfonate heparan 6-sulfonate transferase is derived from Gallus; the sulfonate heparan 3-sulfonate transferase is derived from Mus musculus.
  • the Genbank number of the N-deacetyl/N-sulfonate transferase is NM_001543 (the nucleotide sequence is shown in SEQ ID NO.1); the glucuronic acid C5-allosterase The Genbank number of NP_056369.1 (nucleotide sequence as shown in SEQ ID NO.3); 5); the Genbank number of the heparan sulfonate 6-sulfotransferase is NP_989813.1 (the nucleotide sequence is shown in SEQ ID NO.11); the heparan sulfonate 3-sulfonic acid The Genbank number NP_034604.1 of transferase (nucleotide sequence is as shown in SEQ ID NO.17).
  • the molecular weight of the heparin precursor is 1.1-35 kDa.
  • said N-deacetyl/N-sulfonate transferase, glucuronate C5-mutosterase, sulfonate heparan 2-sulfonate transferase, sulfonate heparan 6-sulfonate transferase The enzyme and heparan sulfonate 3-sulfonate transferase are added to the reaction system separately, or added to the reaction system in the form of mixed enzyme solution.
  • the recombinant bacteria are 1:1:1:1:1, 2:1:1:1:1, 1:2:1:1:1, 1:1:2: 1:1, 1:1:1:2:1 or 1:1:1:1:2 ratio, OD 600 ⁇ 20 corresponding to ratio 1.
  • the recombinant bacteria use Pichia pastoris GS115 as the starting strain, and use pGAPZB, pAO815 or pPIC3.5K as the expression vector.
  • the heparin precursor is obtained by fermentation of E.coli strain Nissle 1917 or E.coli K5, and then heparin lyase I and heparin lyase are added in an amount of not less than 4U/g of heparin precursor III. React for 0-8 hours to obtain heparin precursors with different molecular weights.
  • heparin lyase I and heparin lyase III react at 37°C for different times:
  • the molecular weight of the heparin precursor was 35kDa when the reaction was 0min; the molecular weight of the heparin precursor was 15kDa when the reaction was 15min; the molecular weight of the heparin precursor was 8kD when the reaction was 30min; the molecular weight of the heparin precursor was 4kDa when the reaction was 45min; The molecular weight of the heparin precursor was 1.4kDa when the reaction was 120min; the molecular weight of the heparin precursor was 1.3kDa when the reaction was 120min when the reaction was 240min; the molecular weight of the heparin precursor was 1.2kDa when the reaction was 360min;
  • the heparin lyase III is disclosed in the patent document with the authorized publication number CN111471669B, and is the mutant S264F/Y490K/D321N described therein.
  • the preparation method of the heparin precursor is to pick a single colony, inoculate it into LB medium, cultivate it overnight at 35-40°C, 200-250r/min, and transfer it to a new LB medium , 35 ⁇ 40°C, 200 ⁇ 250r/min cultured for 8 hours, then inoculated into the heparin precursor fermentation medium according to 10% (V/V); during the whole fermentation process, the pH of the fermentation broth was controlled by 1M HCl or 2M NaOH to maintain at 7.0; From the 8th hour of fermentation, add fresh medium (800g/L glucose, 20g/L MgSO 4 ⁇ 7H 2 O and 0.2g/L thiamine) to maintain the glucose concentration in the fermentation broth greater than 10g/L To the end of fermentation, a total of 48 hours of fermentation.
  • the invention provides a method for enzymatically preparing heparin.
  • the method is to add PAPS and heparin-modifying enzyme into a reaction system containing a heparin precursor, and react at 35-45°C for 20-25 hours to prepare heparin; Or add PAPS synthesis bifunctional enzyme and heparin modification enzyme reaction in ATP-containing system to prepare heparin;
  • the heparin modifying enzymes include N-deacetyl/N-sulfotransferase, glucuronate C5-mutosterase, sulfonate heparan 2-sulfotransferase, sulfonate heparan 6-sulfotransferase and sulfonate Acid heparan 3-sulfonate transferase.
  • the N-deacetyl/N-sulfonate transferase is derived from Homo sapiens; the glucuronic acid C5-mutosterase is derived from Homo sapiens; the sulfonate heparan 2-sulfonic acid The transferase is derived from Gallus; the sulfonate heparan 6-sulfonate transferase is derived from Gallus; the sulfonate heparan 3-sulfonate transferase is derived from Mus musculus.
  • the Genbank number of the N-deacetyl/N-sulfonate transferase is NM_001543 (the nucleotide sequence is shown in SEQ ID NO.1); the glucuronic acid C5-allosterase The Genbank number of NP_056369.1 (nucleotide sequence as shown in SEQ ID NO.3); 5); the Genbank number of the heparan sulfonate 6-sulfotransferase is NP_989813.1 (the nucleotide sequence is shown in SEQ ID NO.11); the heparan sulfonate 3-sulfonic acid The Genbank number NP_034604.1 of transferase (nucleotide sequence is as shown in SEQ ID NO.17).
  • the method is to add ATP, MgSO 4 , PAPS to synthesize bifunctional enzyme ASAK S and heparin modifying enzyme into a reaction system containing heparin precursor, React for 20-25 hours to prepare heparin;
  • the heparin modifying enzymes include N-deacetyl/N-sulfonate transferase, glucuronic acid C5-mutosterase, sulfonate heparan 2-sulfonate transferase, sulfonate acetyl Heparin 6-sulfonate transferase and heparan sulfonate 3-sulfonate transferase.
  • the heparin-modifying enzyme is obtained by fermenting a mixture of engineering strains of Pichia pastoris.
  • the PAPS synthetic bifunctional enzymes ASAK S and PPK S are obtained by fermentation of recombinant Escherichia coli, a single colony of Escherichia coli is picked and cultivated overnight in LB medium, and the seeds are inoculated in the In the TB medium, continue to culture until the OD 600 is 0.6-0.8 to induce expression, induction condition: 0.3-0.5mM IPTG induction expression (25°C, 220rpm), induction expression time is 8-12h.
  • the cells were collected by centrifugation, washed with deionized water twice, and the cells were resuspended with PBS solution, then homogenized under high pressure at 800 bar for 5 min, and the supernatant was collected by centrifugation.
  • the ATP concentration is 3-6 g/L
  • the MgSO 4 concentration is 1-3 g/L.
  • the PAPS synthetic bifunctional enzyme ASAK S5 is obtained by using Gene as ID: 853466, the atpsS gene whose nucleotide sequence is shown in SEQ ID NO.22 and GenBank accession number as M74586.1, Its nucleotide sequence is obtained by fusion of the apskE gene shown in SEQ ID NO.23.
  • the GeneID accession number of the PPK S is 878853, and its nucleotide sequence is shown in SEQ ID NO.24.
  • the present invention utilizes synthetic biology technology and genetic engineering means, takes Pichia pastoris GS115 as the starting strain, and heterologously expresses a gene related to the heparin synthesis pathway in the cell: bifunctional N-deacetyl/N-sulfonate transferase (NDST) , glucuronate C5-allosterase (C5 epi), heparan sulfonate 2-sulfotransferase (2-OST), heparan sulfonate 6-sulfotransferase (6-OST), heparan sulfonate 3-sulfotransferase (3-OST), successfully prepared the enzyme solution, and realized the in vitro catalytic synthesis of heparin by the whole enzymatic method for the first time.
  • the anticoagulant activity of the prepared heparin, the anti-FXa activity can reach 89.53ng/mL
  • the anti-FIIa activity can reach 54.53ng/mL.
  • Fig. 1 is a schematic diagram of producing heparin by enzymatic modification of heparin precursor.
  • Figure 2 is the enzymatic activity of NDST1 from different sources.
  • Figure 3 shows the enzyme activity of C5 epi from different sources.
  • Figure 4 is the enzyme activity of 2-OST from different sources.
  • Figure 5 shows the enzyme activity of 6-OST from different sources.
  • Figure 6 is the enzyme activity of 3-OST from different sources.
  • Figure 7 is the change of heparin precursors with different molecular weights over time.
  • Fig. 8 is an LC-MS chart of GlcA-GlcNAc (m/z: 378.3).
  • Fig. 9 is an LC-MS chart of GlcA-GlcNS (m/z: 416.3).
  • Fig. 10 is an LC-MS chart of GlcA-GlcNAc6S (m/z: 458.05).
  • Fig. 11 is an LC-MS chart of IndoA-GlcNS6S (m/z: 496.4).
  • Fig. 12 is an LC-MS chart of IndoA2S-GlcNS6S (m/z: 577.5).
  • Figure 13 is a graph showing the results of anticoagulant activity.
  • Fig. 14 is a graph of heparin prepared by method one.
  • Fig. 15 is a graph of heparin prepared by method two.
  • Pichia pastoris GS115 is preserved in our laboratory.
  • PrimeSTAR DNA polymerase, DNA Marker, Solution I and other enzyme reagents were purchased from TaKaRa (Dalian).
  • ClonExpress one-step directional cloning kit was purchased from Beyotime Biotechnology (Shanghai).
  • the plasmid extraction kit was purchased from Bioengineering (Shanghai) Co., Ltd.
  • Heparin lyase III is disclosed in the patent document with the authorized announcement number CN111471669B, and it is the mutant S264F/Y490K/D321N described therein.
  • NCBI accession number of heparin lyase I WP_055300818.1 (the nucleotide sequence is shown in SEQ ID NO.25).
  • reaction system 50mM Tris-HCl buffer pH 7.5
  • PAPS synthetic bifunctional enzyme 1mg/mL (specific enzyme activity: 18-20U/mg)
  • polyphosphokinase 1mg/mL specific enzyme activity: 15-20U /mg
  • substrate ATP 5g/L magnesium sulfate 3g/L.
  • the PAPS synthetic bifunctional enzyme is added at 0 h after the reaction starts, the polyphosphokinase is added at 10 to 15 hours after the reaction starts, and the reaction is completed after 40 to 50 hours (when no ATP is detected in the reaction system, it is regarded as the end of the reaction), After the reaction, the yield of PAPS was measured, and the PAPS with a purity of 85% was obtained.
  • LB solid medium g/L: peptone 10, yeast powder 5, sodium chloride 10, agar powder 20.
  • LB liquid medium g/L: peptone 10, yeast powder 5, sodium chloride 10.
  • TB liquid medium g/L: peptone 24, yeast powder 12, glycerol 4, K 2 HPO 4 ⁇ 3H 2 O 12.64, KH 2 PO 4 2.31.
  • Seed medium (g/L): 20 peptone, 10 yeast powder, 20 glucose.
  • Pichia recombinant fermentation medium g/L: Glycerol 40, K 2 SO 4 18, MgSO 4 7H 2 O 14.9, KOH 4.13, 85% H 3 PO 4 26.7mL/L, CaSO 4 2H 2 O 0.93, 4.35mL/PTM1 trace element; Among them, PTM1 (g/L): CuSO 4 5H 2 O 6, KI 0.09, MnSO 4 H 2 O 3, H 3 BO 3 0.02, MoNa 2 O 4 2H 2 O 0.2, C°Cl 2 ⁇ 6H 2 O 0.5, ZnCl 2 20, FeSO 4 ⁇ 7H 2 O 65, biotin 0.2, H 2 SO 4 5.0 mL.
  • Heparin precursor fermentation medium glucose 20, thiamine 0.3, KH 2 PO 4 13.5, (NH 4 ) 2 HPO 4 4.0, MgSO 4 7H 2 O 1.4, citric acid 1.7, trace metal ions 10mL.
  • metal ion components g/L: FeSO 4 ⁇ 7H 2 O10, CaCl 2 2.0, ZnSO 4 ⁇ 7H 2 O 2.2, MnSO 4 ⁇ 4H 2 O 0.5, CuSO 4 ⁇ 5H 2 O 1.0, (NH 4 ) 6 Mo 7 O 24 ⁇ 4H 2 O 0.1, Na 2 B 4 O 7 ⁇ 10H 2 O 0.02 were dissolved in 5M HCl.
  • Heparin precursor was produced by fermentation of E.coli strain Nissle 1917 or E.coli K5.
  • E.coli strain Nissle 1917 or E.coli K5 culture conditions Pick a single colony, inoculate into 3mL LB medium, culture overnight at 37°C, 220r/min, transfer to 50mL LB medium, 37°C After culturing at 220r/min for 8h, inoculate into the heparin precursor fermentation medium (3L/7L fermenter) according to 10% (V/V). Throughout the fermentation process, the pH of the fermentation broth was maintained at 7.0 by controlling 1M HCl or 2M NaOH.
  • HPSEC High performance size exclusion chromatography
  • HPSEC system is a set of Agilent 1260 system composed of G1310A pump, G1329B needle and G1362A differential detector .
  • Analysis conditions Chromatographic column: Ultrahydrogel TM Linear column 7.8 ⁇ 300mm; Mobile phase: 0.1mol/L NaNO 3 solution; Flow rate: 0.75mL/min; Column temperature: 37°C; Injection volume: 20 ⁇ L.
  • a standard curve between the molecular weight and the elution volume was prepared using gel permeation chromatography (Gel permeation chromatography, GPC). Under the same conditions, the elution volume of each sample is measured, and the GPC software can calculate the weight average molecular weight, number average molecular weight and molecular weight distribution of each sample.
  • Example 1 Screening of NDST, C5 epi, 2-OST, 6-OST, 3-OST from different sources
  • the gene sequence was synthesized by a gene synthesis company, and the synthesized genes were respectively connected to the polycloning restriction site of pPIC3.5K, and the recombinant plasmids pPIC3.5K-Homo sapiens NDST1 and pPIC3.5K-Mus musculus were respectively constructed NDST1, pPIC3.5K-Homo sapiens C5 epi, pPIC3.5K-Danio rerio C5, pPIC3.5K-Gallus 2-OST, pPIC3.5K-Danio rerio 2-OST, pPIC3.5K-Homo sapiens 2-OST, pPIC3.
  • Pichia pastoris GS115 competent cells linearize the recombinant plasmid obtained above with SalI, and then use electrotransformation into Pichia pastoris GS115 competent cells, electrotransfer into GS115 yeast cells, use MD plate to screen the positive clones obtained, and then use 4mg/mL G418 was used to screen the copy number, and the strains with a copy number greater than 10 were obtained.
  • the strains obtained by screening were cultured in shake flasks: respectively inoculated into 5mL YPD medium at 30°C, cultured at 220rpm for 16-24h, then transferred to 50mL BMGY medium for 24h, and then transferred to BMMY and induced by methanol for 96h. After the end, the cells were washed twice with Tris-HCl (25mmol/L, pH7.4), and the cells were resuspended with 50mL Tris-HCl, and the cells were broken with a high-pressure homogenizer for enzyme activity determination.
  • Tris-HCl 25mmol/L, pH7.4
  • the total activity of NDST was characterized by measuring the content of N-(5-nitro-2-pyridyl)prolinol (PNP): the standard reaction conditions used were 900 ⁇ L of substrate stock solution (50mM PNPS, 0.5mM PAP, 0.5mg ASST IV and 10mg of N-deheparan precursor dissolved in 20mM Tris-HCl (pH 7.4)), preheated at 37°C for 5min, then added 100 ⁇ L of 1g/L NDST, reacted at 37°C for 1h, and added 0.2mL of 10M NaOH solution to terminate the reaction. After centrifuging at 12,000 g for 10 min, the precipitate was removed, and the absorbance value of PNP produced by the enzyme-linked reaction was measured at 400 nm.
  • substrate stock solution 50mM PNPS, 0.5mM PAP, 0.5mg ASST IV and 10mg of N-deheparan precursor dissolved in 20mM Tris-HCl (pH 7.
  • the enzymatic activity of C5epi was determined by C5epi coupled with 2-OST to detect the amount of PNP produced: standard reaction conditions were 900 ⁇ L of substrate stock solution (50 mM PNPS, 0.5 mM PAP, 0.5 mg ASST IV and 10 mg N-sulfated heparin precursor Dissolve in 20mM Tris-HCl (pH 7.4)), preheat at 37°C for 5min, add 100 ⁇ L 1g/L C5 epimerase and 2g/L HS2ST, react at 37°C for 1h, add 0.2mL 10M NaOH solution to terminate reaction. After centrifuging at 12,000 g for 10 min, the precipitate was removed, and the absorbance value of PNP produced by the enzyme-linked reaction was measured at 400 nm.
  • substrate stock solution 50 mM PNPS, 0.5 mM PAP, 0.5 mg ASST IV and 10 mg N-sulfated heparin precursor Dissolve in 20mM Tris-HCl
  • Heparin sulfotransferase (2-OST, 6-OST, 3-OST) enzyme activity was measured using a spectrophotometer to detect the generation of PNP: the standard reaction conditions were 900 ⁇ L of substrate mother solution (50mM PNPS, 0.5mM PAP, 0.5mg ASST Dissolve IV and 10mg heparin in 20mM Tris-HCl (pH7.4)), preheat at 37°C for 5min, add 100 ⁇ L 1g/L sulfotransferase enzyme solution, react at 37°C for 1h, add 0.2mL 10M NaOH solution to terminate the reaction .
  • substrate mother solution 50mM PNPS, 0.5mM PAP, 0.5mg ASST Dissolve IV and 10mg heparin in 20mM Tris-HCl (pH7.4)
  • the precipitate was removed, and the absorbance value of PNP produced by the enzyme-linked reaction was measured at 400 nm.
  • One unit of sulfotransferase activity is defined as the amount of enzyme required to release 1 ⁇ M PNP per hour at pH 7.4 and 37°C.
  • the control reaction was to add an equal amount of inactivated enzyme solution under the same conditions. Three biological repetitions were performed for each reaction, and the average value was taken as the final enzyme activity value.
  • Embodiment 2 Gradual catalytic preparation of heparin
  • the recombinant strains GS115/NDST1, GS115/C5 epi, GS115/2-OST, GS115/6-OST, and GS115/3-OST constructed in Example 1 were subjected to 3-L fed-batch fermentation respectively.
  • single colonies were obtained by dividing and marking, and picked single colonies and inoculated them in 5ml YPD liquid medium, cultured at 30°C, 220rpm for 16-18h, and then transferred to three bottles of 50mL YPD liquid medium according to 10% inoculum amount , cultivated at 30°C and 220rpm for about 24h (OD 600 is 60-70), then inoculated at 15% in a 3-L fermenter containing 1L fermentation medium, controlled fermentation temperature was 28°C, pH was 5.5, and the ventilation rate was 4.0vvm, the stirring speed is related to the dissolved oxygen, the dissolved oxygen is controlled at 30%, and the stirring speed is 300-1000rpm.
  • the acceleration rate of methanol flow and the final concentration of methanol in the medium were controlled by a methanol detector on-line in real time for 108 hours of induction. Collect the bacterial cells obtained from fermentation, wash the bacterial cells twice with deionized water, resuspend the bacterial cells, use high-pressure homogenization to break the wall, and then centrifuge to obtain the intracellular supernatant.
  • Reaction system for the preparation of N-sulfonated heparin precursor (-GlcA-GlcNS-) (p01): the concentration of heparin precursor in the reaction system is 1g/L, add excess NDST1 enzyme solution to it, and the final concentration of PAPS is 0.5g/L (excessive amount), react at 37°C, pH7.4 for 24h.
  • Figure 8 and Figure 9 show that the N-sulfonated heparin precursor containing the -GlcA-GlcNS- structure was successfully prepared with a conversion rate of 91%.
  • the molecular weight of heparin precursor is obtained by controlling the concentration and reaction time of heparin lyase I and III, and the reaction system is carried out in 50mmol/L Tris-HCl (pH7.4) buffer solution: final concentration 1g/L heparin precursor, 10 ⁇ l 4U/L heparin lyase I, 10 ⁇ l 4U/mL heparin lyase III, react at 37°C. After the reaction, the heparin precursor and the molecular weight of heparin were detected.
  • the molecular weight of heparin precursor was 35kDa at 0min
  • the molecular weight of heparin precursor was 15kDa at 15min, 8kDa at 30min, 4kDa at 45min, and 4kDa at 60min. 2kDa
  • the molecular weight of heparin precursor is 1.4kDa when reacting for 120min
  • the molecular weight of heparin precursor is 1.3kDa when reacting for 120min when reacting for 240min
  • the molecular weight of heparin precursor is 1.2kDa when reacting for 360min
  • the molecular weight of heparin precursor is 1.1kDa when reacting for 480min.
  • Example 4 Recombinant Escherichia coli fermentation culture to obtain PAPS synthetic bifunctional enzymes ASAK S and PPK S
  • the PAPS used in this embodiment synthesizes bifunctional enzyme ASAK S5 (Gene is ID: 853466, and its nucleotide sequence is as shown in SEQ ID NO.22 atpsS gene and GenBank accession number are M74586.1, and its nucleotide sequence is as SEQ ID NO.22
  • the expression, purification and preparation of the apskE gene fusion shown in ID NO.23) and PPKS (GeneID accession number is 878853, its nucleotide sequence is shown in SEQ ID NO.24) are obtained according to the literature (Closed-Loop System Driven by ADP Phosphorylation from Pyrophosphate Affords Equimolar Transformation of ATP to 3'-Phosphoadenosine-5'-phosphosphate, 2021).
  • Example 5 Construction of a sulfonation modification system for preparing different molecular weight heparins based on PAPS
  • NDST1, C5 epi, 2-OST, 6-OST, 3-OST are obtained from shake flask culture or fermenter.
  • the catalytic reaction is carried out in 50mL 50mmol/L MES (pH7.4) buffer solution: 5mL 10g /L different molecular weight heparin precursors, 5mL 3500U/L NDST1, 5mL 3500U/L C5 epi, 5mL 3500U/L 2-OST, 5mL 3500U/L 6-OST, 5mL 3500U/L 3-OST and a final concentration of 0.5g /L of PAPS, reacted at 40°C for 24 hours, and collected the reaction solution.
  • the samples containing ethanol were freeze-dried to obtain samples of heparin with different molecular weights with a yield of 20 g/L and an average purity of more than 80%.
  • Example 6 Construction of a sulfonation modification system for preparing different molecular weight heparins from ATP
  • NDST1, C5 epi, 2-OST, 6-OST, 3-OST are obtained from shake flask culture or fermenter.
  • the catalytic reaction is carried out in 50mL 50mmol/L MES (pH7.4) buffer solution: 5mL 10g /L different molecular weight heparin precursors, 5mL 3500U/L NDST1, 5mL 3500U/L C5-epi, 5mL 3500U/L 2-OST, 5mL 3500U/L 6-OST, 5mL 3500U/L 3-OST, 10 ⁇ M ASAK S5 , 0.5g/L PPK S , ATP at a final concentration of 5g/L, and MgSO 4 at 2g/L were reacted at 40°C for 48h, and the reaction solution was collected.
  • Example 5 the ethanol precipitation method was used to separate and purify macromolecular heparin and low molecular weight heparin to obtain heparin with different molecular weights.
  • Example 7 Pichia pastoris co-culture simplified heparin production process
  • the primary seed liquid is to inoculate GS115/NDST1, GS115/C5 epi, GS115/2-OST, GS115/6-OST, GS115/3-OST into 5mL YPD medium and cultivate for 16h (OD 600 ⁇ 6.0), the secondary seed
  • the specific enzyme-catalyzed reaction is carried out in 50mL 50mmol/L MES (pH7.4) buffer solution: at 40°C, add 25mL of an appropriate amount of mixed enzyme solution to a final concentration of 0.5g/L PAPS and different final concentrations of heparin precursor (0.5g /L, 0.4g/L, 0.3g/L, 0.2g/L, 0.1g/L) to prepare heparin with different degrees of sulfonation, mix well, and fully react at 40°C for 24h. After the reaction, the product was boiled for 5 min, centrifuged to remove impurity proteins, and the supernatant was ethanol-precipitated twice by ethanol precipitation. Using LC-MS to identify the distribution of sulfonated disaccharides at different positions is shown in the table below:
  • the product was purified using a HiPrep Q HP 16/10 column.
  • Example 8 Preparation of heparin with different anticoagulant activities by co-culture of different proportions of Pichia pastoris
  • Example 7 the ratio of NDST1: C5 epi: 2OST: 6 OST: 3OST is replaced by 2:1:1:1:1, 1:2:1:1:1, 1:1:2:1:1 , 1:1:1:2:1, 1:1:1:1:2 (ratio 1 corresponds to OD 600 ⁇ 20), cultivated in a 3-L bioreactor according to the above culture method, and prepared heparin according to the following two methods : Method 1, add 0.5g/L PAPS and 0.1g/L heparin precursor to 50mL of different mixed enzyme solutions, mix well, fully react at 40°C for 24h Method 2, add 50mL of different mixed enzyme solutions to 10 ⁇ M ASAK S5 , 0.5g/L PPK S , ATP at a final concentration of 5g/L, and MgSO 4 at 2g/L were fully reacted at 40°C for 24 hours to prepare heparin with anticoagulant activity.
  • Method 1 add 0.5g/L PAPS and 0.1g/L heparin precursor to 50
  • Embodiment 9 Preparation of different molecular weight heparins
  • Heparin precursors with different molecular weights 35kDa, 15kDa, 8kDa, 4kDa, 2kDa, 1.4kDa, 1.3kDa, 1.2kDa, 1.1kDa
  • the inoculation ratio is obtained by mixing the enzyme solution in 50mL 50mmol/L MES (pH7.4) buffer solution to carry out the following two catalytic reactions:
  • heparin sample prepared in Example 6 Take 500 ⁇ l of the heparin sample prepared in Example 6, add 10 ⁇ l of 4U/L heparin lyase I and 4U/L heparin lyase III, and place it in a water bath at 37°C for 10 hours. The lysed solution was heated at 90°C for 10 minutes to inactivate and denature the protein, and after centrifugation, the supernatant was collected for LC-MS detection.
  • LC-MS detection uses a HILIC column (3 ⁇ m, 2.0 ⁇ 150 mm, YMC, Japan). Eluent A is ultrapure water, and eluent B is acetonitrile.
  • the elution gradient used was set as follows: 0-2 minutes, 90% B; 2-8 minutes, 90-50% B; 8-12 minutes, 50% B; 12-13 minutes, 90% B.
  • the column temperature was maintained at 35 °C, and the flow rate was 0.2 mL/min.
  • the mass range of m/z 100-800 was scanned and monitored in negative ion mode.
  • the mass-to-charge ratio of the disaccharide molecule of heparin should contain the following ion currents in negative ion mode: m/z: 378.3, m/z: 416.3, m/z: 496.4, m/z: 458.05, m/z: 577.6. From the mass spectrometry results shown in Fig. 8, Fig. 9, Fig. 10, Fig. 11 and Fig. 12, it can be seen that this embodiment realizes the synthesis of heparins with different molecular weights.
  • Example 11 Determination of anticoagulant activity of heparin
  • heparin precursor and bioengineering heparin prepared by recombinant bacteria in different proportions measure its anticoagulant active.
  • FXa factor and human ATIII were diluted to 60nM and 0.65pM with PBS containing 1mg/mL bovine serum albumin (BSA).
  • BSA bovine serum albumin
  • Chromogenic substrates S-2765 and S-2238 were dissolved in water to prepare 1 mg/mL stock solution.
  • the oligosaccharides used in the test were diluted with PBS to a concentration of 200 nM.
  • the absorbance of the reaction mixture was measured at 405 nm, and the IC50 of the test oligosaccharide was calculated by plotting different sample concentrations against the initial reaction rate.
  • Example 5 0.5g/L, 0.4g/L, 0.3g/L, 0.2g/L, 0.1g/L concentration of heparin precursor and the biological preparation obtained by recombinant bacteria in a ratio of 1:1:1:1:1
  • the anti-FXa factor and anti-FIIa factor activities of the engineered heparin were evaluated by in vitro colorimetry (the left column indicates the anti-FXa factor activity, and the right column indicates the anti-IIa factor activity).
  • the anti-Fxa activity of heparin obtained by adding 0.1g/L heparin precursor was 79.94ng/mL, and the anti-IIa activity was 37.07ng/mL, similar to the heparin of Sango Biotechnology (Shanghai) ( Figure 13 Heparin) , but higher than other bioengineered heparins, the ratio of anti-Fxa/anti-FIIa (2.16 ⁇ 0.31).

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Abstract

一种制备不同分子量肝素的磺酸化修饰体系构建及其应用，属于生物工程技术领域。利用合成生物学技术和基因工程手段，以毕赤酵母GS115为出发菌株，在细胞内异源表达了肝素合成途径相关基因：双功能N－脱乙酰/N－磺酸转移酶(NDST)、葡萄糖醛酸C5-变构酶(C5epi)、磺酸乙酰肝素2-磺酸转移酶(2-OST)、磺酸乙酰肝素6-磺酸转移酶(6-OST)、磺酸乙酰肝素3-磺酸转移酶(3-OST)，所述方法实现了利用微生物发酵碳源生产肝素修饰酶，并首次实现了从ATP出发全酶法体外催化合成肝素。

Description

制备不同分子量肝素的磺酸化修饰体系构建及其应用 技术领域
本发明涉及制备不同分子量肝素的磺酸化修饰体系构建及其应用，属于生物医药领域。
背景技术
肝素是一类具有多种生物学功能的糖胺聚糖，由GlcA及GlcNAc经β-1,4、α-1,4糖苷键连接并经变构化、磺酸化修饰而成。动物体内几乎每种类型的细胞都具有合成肝素的能力。肝素以蛋白聚糖形式广泛存在于细胞表面或细胞外基质中。肝素与多种蛋白配体相互作用从而调节一系列生物学活性，包括发育过程、血管形成、血液凝固和肿瘤转移等。
肝素形成由二糖单元-GlcA-GlcNAc-组成的多糖骨架后，首先是应用具有两种催化功能的N－脱乙酰/N－磺酸转移酶(N-deacetylase/N-sulfotransferases,NDST)将GlcNAc的乙酰基脱掉形成含有自由氨基的葡萄糖胺(GlcNAc)，然后N－磺酸转移酶转移一个磺酸基团到葡萄糖胺形成GlcNS。磺酸转移酶与磺酸基团的供体3’-磷酸－腺苷-5’－磷酰磺酸(3’-phosphoadenosine5/phosphosulfate，PAPS)相互作用将磺酸基团转移到糖单元相应的位置。葡萄糖胺N-位磺酸化修饰后，D-GlcA通过差向异构酶(C5-epimerase，C5-epi)形成L-IdoA，紧接着2-磺酸转移酶(2-sulfotransferases，2-OSTs)将磺酸基团转移到IdoA或GlcA的C2位形成IdoA2S或GlcA2S。然后GlcNS的C6位和C3位分别通过6-磺酸转移酶(6-sulfotransferases，6-OSTs)和3-磺酸转移酶(3-sulfotransferases，3-OSTs)发生磺酸化修饰。
目前商品化的肝素严重依赖于动物组织提取(肝脏，猪小肠等)，该方法存在许多问题，比如原料周期长，潜在动物病毒传染，环境污染，组织提取的肝素结构高度不均一，存在潜在的致病因子。动物组织来源的肝素作为临床上广泛使用的药物一直面临结构不稳定、成分复杂的问题。由于肝素中混有一定量的过磺酸软骨素造成了2007-2008年的百特伦事件。为了得到结构均一性较好、生物安全的肝素，利用微生物酶法进行肝素的合成可以有效避免上述问题。
发明内容
本发明为实现绿色高效制备肝素的目的，以毕赤酵母为平台菌株，分别表达肝素修饰酶(NDST1，C5 epi，2-OST，6-OST1和3-OST1)，并通过体系优化制备肝素修饰酶，制备不同磺酸化程度的肝素，此外，采用毕赤酵母共培养体系，通过体外添加PAPS及从ATP出发制备得到不同分子量的肝素。由于生物酶法具有反应条件温和、专一性高、产物易控制等优点，易于实现工业化生产制备肝素。
本发明通过系统优化，将多个催化体系有机的组合形成了一个可以通过多酶级联反应高效催化合成肝素的方法。本方法通过两种方式：(1)肝素前体、肝素修饰酶和PAPS或(2)肝素前体、肝素修饰酶、PAPS合成双功能酶ASAK S、PPK S、ATP和MgSO 4反应即可得到最终肝素。本方法操作简便，成本低廉，有着重大的实用价值。
本发明的目的在于为了克服现有技术中的问题，实现微生物酶法定向生产肝素，克服了传统的组织提取法带来的各种弊端，及常规化学酶法催化合成肝素过程的低效和繁琐，并大大降低了生产成本。
本发明的目的是为了克服现有技术中的问题，通过毕赤酵母表达肝素修饰酶实现不同分子量肝素的合成，然后通过甲醇为诱导剂诱导肝素修饰酶的表达，实现以不同分子量肝素前体为底物，全酶法定向生产分子量范围1.1-38.02kDa的肝素。
本发明提供了一种对肝素前体磺酸化修饰的方法，所述方法为在含有肝素前体的体系中，加入PAPS和肝素修饰酶，所述肝素修饰酶包括N－脱乙酰/N－磺酸转移酶、葡萄糖醛酸C5-变构酶、磺酸乙酰肝素2-磺酸转移酶、磺酸乙酰肝素6-磺酸转移酶和磺酸乙酰肝素3-磺酸转移酶。
在一种实施方式中，所述N－脱乙酰/N－磺酸转移酶来源于Homo sapiens；所述葡萄糖醛酸C5-变构酶来源于Homo sapiens；所述磺酸乙酰肝素2-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素6-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素3-磺酸转移酶来源于Mus musculus。
在一种实施方式中，所述N－脱乙酰/N－磺酸转移酶的Genbank号为NM_001543(核苷酸序列如SEQ ID NO.1所示)；所述葡萄糖醛酸C5-变构酶的Genbank号为NP_056369.1(核苷酸序列如SEQ ID NO.3所示)；所述磺酸乙酰肝素2-磺酸转移酶的Genbank号为NP_989812.1(核苷酸序列如SEQ ID NO.5所示)；所述磺酸乙酰肝素6-磺酸转移酶的Genbank号为NP_989813.1(核苷酸序列如SEQ ID NO.11所示)；所述磺酸乙酰肝素3-磺酸转移酶的Genbank号NP_034604.1(核苷酸序列如SEQ ID NO.17所示)。
在一种实施方式中，将肝素修饰酶同时或逐级添加至反应体系中。
在一种实施方式中，所述逐级添加为先将N－脱乙酰/N－磺酸转移酶加入含有肝素前体和PAPS的反应体系中反应；反应结束后，再将葡萄糖醛酸C5-变构酶和磺酸乙酰肝素2-磺酸转移酶加入反应体系中反应；反应结束后，向反应体系中加入磺酸乙酰肝素6-磺酸转移酶反应；反应结束后，再加入磺酸乙酰肝素3-磺酸转移酶反应。
在一种实施方式中，PAPS相较于肝素前体过量添加，即肝素前体与PAPS摩尔比大于 1:1。
本发明提供了一种制备不同分子量肝素的方法，所述方法是以不同分子量的肝素前体为底物，加入PAPS、N－脱乙酰/N－磺酸转移酶、葡萄糖醛酸C5-变构酶、磺酸乙酰肝素2-磺酸转移酶、磺酸乙酰肝素6-磺酸转移酶和磺酸乙酰肝素3-磺酸转移酶，催化生成得到不同分子量的肝素；
或是，在含有ATP的体系中，加入PAPS合成双功能酶，加入肝素修饰酶反应，生成得到不同分子量的肝素；
所述N－脱乙酰/N－磺酸转移酶来源于Homo sapiens；所述葡萄糖醛酸C5-变构酶来源于Homo sapiens；所述磺酸乙酰肝素2-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素6-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素3-磺酸转移酶来源于Mus musculus。
在一种实施方式中，所述N－脱乙酰/N－磺酸转移酶的Genbank号为NM_001543(核苷酸序列如SEQ ID NO.1所示)；所述葡萄糖醛酸C5-变构酶的Genbank号为NP_056369.1(核苷酸序列如SEQ ID NO.3所示)；所述磺酸乙酰肝素2-磺酸转移酶的Genbank号为NP_989812.1(核苷酸序列如SEQ ID NO.5所示)；所述磺酸乙酰肝素6-磺酸转移酶的Genbank号为NP_989813.1(核苷酸序列如SEQ ID NO.11所示)；所述磺酸乙酰肝素3-磺酸转移酶的Genbank号NP_034604.1(核苷酸序列如SEQ ID NO.17所示)。
在一种实施方式中，所述肝素前体的分子量为1.1～35kDa。
在一种实施方式中，所述N－脱乙酰/N－磺酸转移酶、葡萄糖醛酸C5-变构酶、磺酸乙酰肝素2-磺酸转移酶、磺酸乙酰肝素6-磺酸转移酶和磺酸乙酰肝素3-磺酸转移酶分别添加至反应体系中，或以混合酶液的形式加入反应体系。
在一种实施方式中，所述混合酶液，是利用重组菌按比例接种，发酵得到的，所述重组菌为分别表达N－脱乙酰/N－磺酸转移酶、葡萄糖醛酸C5-变构酶、磺酸乙酰肝素2-磺酸转移酶、磺酸乙酰肝素6-磺酸转移酶和磺酸乙酰肝素3-磺酸转移酶的重组毕赤酵母，所述重组菌按菌浓＝(1～2):(1～2):(1～2):(1～2):(1～2)的比例混合，加入毕赤酵母发酵培养基发酵得到。
在一种实施方式中，所述重组菌按菌浓1:1:1:1:1、2:1:1:1:1，1:2:1:1:1，1:1:2:1:1，1:1:1:2:1或1:1:1:1:2的比例，比例1对应的OD 600≈20。
在一种实施方式中，所述重组菌以毕赤酵母GS115为出发菌株，以pGAPZB、pAO815或pPIC3.5K为表达载体。
在一种实施方式中，所述肝素前体是由E.coli strain Nissle 1917或E.coli K5发酵得到，再按不低于4U/g肝素前体的量加入肝素裂解酶I和肝素裂解酶III，反应0～8h，得到不同分 子量的肝素前体。
在一种实施方式中，向肝素前体中加入肝素裂解酶I和肝素裂解酶III后，在37℃下，反应不同时间：
反应0min时肝素前体分子量为35kDa；反应15min时肝素前体分子量为15kDa；反应30min时肝素前体分子量为8kD；应45min时肝素前体分子量为4kDa；反应60min时肝素前体分子量为2kDa；反应120min时肝素前体分子量为1.4kDa；反应240min时反应120min时肝素前体分子量为1.3kDa；反应360min时肝素前体分子量为1.2kDa；反应480min时肝素前体分子量为1.1kDa。
在一种实施方式中，所述肝素裂解酶III公开于授权公告号CN111471669B的专利文献中，为其中记载的突变体S264F/Y490K/D321N。
在一种实施方式中，所述肝素前体的制备方法为挑取单菌落，接种至LB培养基中，35～40℃，200～250r/min过夜培养，转接至新的LB培养基中，35～40℃，200～250r/min培养8h后按照10％(V/V)接种到肝素前体发酵培养基；在整个发酵过程中，通过1M HCl或2M NaOH控制发酵液的pH维持在7.0；从发酵第8小时开始，流加新鲜的培养基(800g/L葡萄糖，20g/L MgSO 4·7H 2O及0.2g/L硫胺素)维持发酵液中的葡萄糖浓度大于10g/L至发酵结束，总共发酵48h。
本发明提供了一种酶法制备肝素的方法，所述方法是向在含有肝素前体的反应体系中，加入PAPS和肝素修饰酶，在35～45℃下反应20～25h，制备得到肝素；或是在含有ATP的体系中，加入PAPS合成双功能酶和肝素修饰酶反应，制备得到肝素；
所述肝素修饰酶包括N－脱乙酰/N－磺酸转移酶、葡萄糖醛酸C5-变构酶、磺酸乙酰肝素2-磺酸转移酶、磺酸乙酰肝素6-磺酸转移酶和磺酸乙酰肝素3-磺酸转移酶。
在一种实施方式中，所述N－脱乙酰/N－磺酸转移酶来源于Homo sapiens；所述葡萄糖醛酸C5-变构酶来源于Homo sapiens；所述磺酸乙酰肝素2-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素6-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素3-磺酸转移酶来源于Mus musculus。
在一种实施方式中，所述N－脱乙酰/N－磺酸转移酶的Genbank号为NM_001543(核苷酸序列如SEQ ID NO.1所示)；所述葡萄糖醛酸C5-变构酶的Genbank号为NP_056369.1(核苷酸序列如SEQ ID NO.3所示)；所述磺酸乙酰肝素2-磺酸转移酶的Genbank号为NP_989812.1(核苷酸序列如SEQ ID NO.5所示)；所述磺酸乙酰肝素6-磺酸转移酶的Genbank号为NP_989813.1(核苷酸序列如SEQ ID NO.11所示)；所述磺酸乙酰肝素3-磺酸转移酶的 Genbank号NP_034604.1(核苷酸序列如SEQ ID NO.17所示)。
在一种酶法制备肝素的方法中，所述方法是向在含有肝素前体的反应体系中，加入ATP、MgSO 4、PAPS合成双功能酶ASAK S和肝素修饰酶，在35～45℃下反应20～25h，制备得到肝素；所述肝素修饰酶包括N－脱乙酰/N－磺酸转移酶、葡萄糖醛酸C5-变构酶、磺酸乙酰肝素2-磺酸转移酶、磺酸乙酰肝素6-磺酸转移酶和磺酸乙酰肝素3-磺酸转移酶。
在一种实施方式中，所述肝素修饰酶是由毕赤酵母工程菌株混菌发酵获得。
在一种实施方式中，所述PAPS合成双功能酶ASAK S和PPK S是由重组大肠杆菌发酵获得，挑取大肠杆菌单菌落于LB培养基中过夜培养，将种子按照2％接种量接种于TB培养基中，继续培养至OD 600为0.6-0.8时进行诱导表达，诱导条件：0.3-0.5mM的IPTG诱导表达(25℃，220rpm)，诱导表达时间为8-12h。然后离心收集菌体，用去离子水洗涤菌体2次后，用PBS溶液重悬细胞，然后在800bar条件下高压匀浆破壁5min，离心收集破壁上清液。
在一种实施方式中，所述ATP浓度为3-6g/L，MgSO 4浓度为1-3g/L。
在一种实施方式中，所述PAPS合成双功能酶ASAK S5是通过将Gene为ID:853466，其核苷酸序列如SEQ ID NO.22所示的atpsS基因和GenBank登录号为M74586.1，其核苷酸序列如SEQ ID NO.23所示的apskE基因融合得到的，所述PPK S的GeneID登录号为878853，其核苷酸序列如SEQ ID NO.24所示。
本发明的有益效果：
本发明利用合成生物学技术和基因工程手段，以毕赤酵母GS115为出发菌株，在细胞内异源表达了肝素合成途径相关基因：双功能N－脱乙酰/N－磺酸转移酶(NDST)、葡萄糖醛酸C5-变构酶(C5 epi)、磺酸乙酰肝素2-磺酸转移酶(2-OST)、磺酸乙酰肝素6-磺酸转移酶(6-OST)、磺酸乙酰肝素3-磺酸转移酶(3-OST)，成功制备得到了酶液，并首次实现了全酶法体外催化合成肝素，制备得到的肝素抗凝血活性，抗FXa活性可达89.53ng/mL，抗FIIa活性可达54.53ng/mL。
附图说明
图1是全酶法修饰肝素前体生产肝素示意图。
图2是不同来源NDST1酶活。
图3是不同来源C5 epi酶活。
图4是不同来源2-OST酶活。
图5是不同来源6-OST酶活。
图6是不同来源3-OST酶活。
图7是不同分子量肝素前体随时间变化。
图8是GlcA-GlcNAc(m/z：378.3)的LC-MS图。
图9是GlcA-GlcNS(m/z：416.3)的LC-MS图。
图10是GlcA-GlcNAc6S(m/z：458.05)的LC-MS图。
图11是IndoA-GlcNS6S(m/z：496.4)的LC-MS图。
图12是IndoA2S-GlcNS6S(m/z：577.5)的LC-MS图。
图13是抗凝血活性结果图。
图14是方法一制备得到的肝素图。
图15是方法二制备得到的肝素图。
具体实施方式
材料：
1.毕赤酵母GS115保藏于本研究室。
2.PrimeSTAR DNA聚合酶、DNA Marker、Solution I等酶类试剂购自TaKaRa(大连)。
3.ClonExpress一步法定向克隆试剂盒购自Beyotime Biotechnology(上海)。
4.胶回收试剂盒，快切酶购自Thermo fisher Scientific公司。
5.质粒抽提试剂盒购自生物工程(上海)有限公司。
6.各种分析纯试剂购自国药集团。
7.GS115感受态制备方法及转化步骤参照Thermo Fisher Invitrogen's Pichia EasyCompo Kit。
8.肝素裂解酶III公开于授权公告号CN111471669B的专利文献中，为其中记载的突变体S264F/Y490K/D321N。
肝素裂解酶I的NCBI登录号：WP_055300818.1(核苷酸序列如SEQ ID NO.25所示)。
9.下述实施例中所使用的PAPS，其制备方法参见公布号为CN113046403A的发明专利及文章Xu,R.et al.Closed-Loop System Driven by ADP Phosphorylation from Pyrophosphate Affords Equimolar Transformation of ATP to 3′-Phosphoadenosine-5′-phosphosulfate.ACS Catalysis,10405-10415(2021).，具体为：利用所述专利文件中制备得到的双功能酶和谷氨酸棒杆菌来源的聚磷酸激酶合成PAPS；
100mL的反应体系(50mM Tris-HCl buffer pH 7.5)，其中，PAPS合成双功能酶1mg/mL(比酶活：18～20U/mg)，聚磷酸激酶1mg/mL(比酶活：15～20U/mg)，底物ATP 5g/L，硫酸镁3g/L。其中PAPS合成双功能酶加入时间为反应开始后0h，聚磷酸激酶加入的时间为 反应开始后10～15h，反应40～50h完成反应(反应体系中没有ATP检出时即视为反应结束)，反应结束后测定PAPS的产量，得到纯度为85％的PAPS。
10.培养基：
LB固体培养基(g/L)：蛋白胨10，酵母粉5，氯化钠10，琼脂粉20。
LB液体培养基(g/L)：蛋白胨10，酵母粉5，氯化钠10。
TB液体培养基(g/L)：蛋白胨24，酵母粉12，甘油4，K 2HPO 4·3H 2O 12.64，KH 2PO 42.31。
种子培养基(g/L)：蛋白胨20，酵母粉10，葡萄糖20。
毕赤酵母重组菌发酵培养基(g/L)：甘油40，K 2SO 4 18，MgSO 4·7H 2O 14.9，KOH 4.13，85％H 3PO 4 26.7mL/L，CaSO 4·2H 2O 0.93，4.35mL/PTM1微量元素；其中，PTM1(g/L)：CuSO 4·5H 2O 6，KI 0.09，MnSO 4·H 2O 3，H 3BO 3 0.02，MoNa 2O 4·2H 2O 0.2，C℃l 2·6H 2O 0.5，ZnCl 2 20，FeSO 4·7H 2O 65，生物素0.2，H 2SO 4 5.0mL。
肝素前体发酵培养基(g/L)：葡萄糖20，硫胺素0.3，KH 2PO 4 13.5，(NH 4) 2HPO 4 4.0，MgSO 4·7H 2O 1.4，柠檬酸1.7，微量金属离子10mL。其中，金属离子组分(g/L)：FeSO 4·7H 2O10，CaCl 2 2.0，ZnSO 4·7H 2O 2.2，MnSO 4·4H 2O 0.5，CuSO 4·5H 2O 1.0，(NH 4) 6Mo 7O 24·4H 2O 0.1，Na 2B 4O 7·10H 2O 0.02溶于5M的HCl中。
11.肝素前体的制备
利用E.coli strain Nissle 1917或E.coli K5发酵生产肝素前体。
(1)E.coli strain Nissle 1917或E.coli K5培养条件：挑取单菌落，接种至3mL LB培养基中，37℃，220r/min过夜培养，转接至50mL LB培养基中，37℃，220r/min培养8h后按照10％(V/V)接种到肝素前体发酵培养基(3L/7L发酵罐)。在整个发酵过程中，通过1M HCl或2M NaOH控制发酵液的pH维持在7.0。从第8小时开始，流加新鲜的培养基(800g/L葡萄糖，20g/L MgSO 4·7H 2O及0.2g/L硫胺素)维持发酵液中的葡萄糖浓度大于10g/L至发酵结束(48h)。
(2)E.coli strain Nissle 1917培养结束后，8,000g离心收集上清。加入终浓度为15g/L的NaCl，3倍体积的乙醇，-80℃冷冻过夜。12,000g，4℃离心收集沉淀，20mM Tris-HCl(pH 7.4)重悬沉淀。加入终浓度为1mg/L的DNase，37℃反应1h去除溶液中的杂质DNA。加入2.5mg/mL的蛋白酶K，55℃反应2h除去溶液中的蛋白。12,000g，4℃离心收集上清，过0.22μm水膜后，过AMBERLITE TM FPA98 Cl树脂吸附软骨素，所得洗脱液经AMBERLITE TM IR120Na树脂除去阳离子杂质，最后经DOWEX*OPTIPORE*L493脱色和
Figure PCTCN2022117166-appb-000001
FILMTEC TM 浓缩后冷冻干燥得到纯度为90％的肝素前体样品。
12.肝素前体及肝素分子量大小的测定：使用高效体积排阻色谱系统(High performance size exclusion chromatography，HPSEC)：HPSEC体系是由G1310A泵和G1329B针头和G1362A示差检测器组成的一套安捷伦1260系统。分析条件：色谱柱：Ultrahydrogel TM Linear column 7.8×300mm；流动相：0.1mol/L NaNO 3溶液；流速：0.75mL/min；柱温：37℃；进样量：20μL。根据葡聚糖标准样品的洗脱体积，使用凝胶渗透色谱分析法(Gel permeation chromatography，GPC)制作出分子量和洗脱体积之间的标准曲线。在相同的条件下，测出每个样品的洗脱体积，GPC软件可计算出每个样品的重均分子量、数均分子量及分子量分布。
实施例1：不同来源的NDST、C5 epi、2-OST、6-OST、3-OST筛选
(1)选取不同来源的NDST、C5 epi、2-OST、6-OST、3-OST，如表1所示。
表1不同来源的基因及其Genbank号
Figure PCTCN2022117166-appb-000002
Figure PCTCN2022117166-appb-000003
(2)基因序列由基因合成公司合成，将合成得到的基因分别连接至pPIC3.5K的多克隆酶切位点处，分别构建得到重组质粒pPIC3.5K-Homo sapiens NDST1、pPIC3.5K-Mus musculus NDST1、pPIC3.5K-Homo sapiens C5 epi、pPIC3.5K-Danio rerio C5、pPIC3.5K-Gallus 2-OST、pPIC3.5K-Danio rerio 2-OST、pPIC3.5K-Homo sapiens 2-OST、pPIC3.5K-Mus musculus 2-OST、pPIC3.5K-Rattus norvegicus 2-OST、pPIC3.5K-Xenopus laevis 2-OST、pPIC3.5K-Gallus 6-OST、pPIC3.5K-Danio rerio 6-OST、pPIC3.5K-Gallus gallus 6-OST、pPIC3.5K-Homo sapiens 6-OST1、pPIC3.5K-Homo sapiens 6-OST3、pPIC3.5K-Mus musculus 6-OST、pPIC3.5K-Danio rerio 3-OST、pPIC3.5K-Homo sapiens 3-OST3、pPIC3.5K-Homo sapiens 3-OST5、pPIC3.5K-Mus musculus 3-OST；
制备毕赤酵母GS115感受态细胞，将上述得到的重组质粒使用SalI线性化后使用电转化至毕赤酵母GS115感受态中，电转到GS115酵母细胞中，使用MD平板筛选得到的阳性克隆，之后使用4mg/mL G418筛选拷贝数，筛选获得拷贝数大于10的菌株。
将筛选获得的菌株进行摇瓶培养：分别接种至5mL YPD培养基30℃，220rpm培养16-24h培养后转接至50mL BMGY培养基培养24h，之后转接BMMY并进行甲醇诱导培养96h，将培养结束后的菌体用Tris-HCl(25mmol/L，pH7.4)洗两遍细胞，并用50mL Tris-HCl重悬菌体，用高压匀浆仪破碎细胞进行酶活测定。
(3)酶活测定：
通过测定N-(5-硝基-2-吡啶基)脯氨醇(PNP)的含量来表征NDST总活力：所用标准反应条件为900μL的底物母液(50mM PNPS，0.5mM PAP，0.5mg ASST IV和10mg N-脱乙酰肝素前体溶解在20mM Tris-HCl(pH 7.4)中)，37℃预热5min后加入100μL 1g/L NDST，37℃反应1h，加入0.2mL 10M NaOH溶液终止反应。12,000g离心10min后去除沉淀，400nm下测定酶联反应产生的PNP的吸光值。
C5epi的酶活测定采用C5epi与2-OST偶联测定检测PNP的生成量：标准反应条件为900μL的底物母液(50mM PNPS，0.5mM PAP，0.5mg ASST IV和10mg N-硫酸化肝素前体溶解在20mM Tris-HCl(pH 7.4)中)，37℃预热5min后加入100μL 1g/L的C5差向异构酶和2g/L的HS2ST，37℃反应1h后加入0.2mL 10M NaOH溶液终止反应。12,000g离心10min 后去除沉淀，400nm下测定酶联反应产生的PNP的吸光值。
肝素磺基转移酶(2-OST、6-OST、3-OST)酶活测定采用分光光度计检测PNP的生成：标准反应条件为900μL的底物母液(50mM PNPS，0.5mM PAP，0.5mg ASST IV和10mg肝素溶解在20mM Tris-HCl(pH7.4)中)，37℃预热5min后加入100μL 1g/L的磺基转移酶酶液，37℃反应1h后加入0.2mL 10M NaOH溶液终止反应。12,000g离心10min后去除沉淀，400nm下测定酶联反应产生的PNP的吸光值。一个硫酸转移酶的酶活单位定义为在pH7.4，37℃条件下，每小时释放1μM PNP所需要的酶量。对照反应为相同条件下加入等量已灭活的酶液。每个反应均做3个生物学重复，取平均值为最终的酶活值。
(4)得到以下几种的来源酶活较高的基因，来源于Homo sapiens的NDST1(NM_001543，SEQ ID NO.1)。来源于Homo sapiens的C5 epi(NP_056369.1，SEQ ID NO.3)，来源于Gallus的2-OST(NP_989812.1，SEQ ID NO.5)，来源于Gallus的6-OST(NP_989813.1，SEQ ID NO.11)，来源于Mus musculus的3-OST(NP_034604.1，SEQ ID NO.17)，将含有相应基因的菌株分别命名为：GS115/NDST1、GS115/C5 epi、GS115/2-OST、GS115/6-OST、GS115/3-OST，经测定，酶活分别为：45U/L，105U/L，203U/L，345.5U/L，257U/L(图2～图6)，用于体外酶法生产肝素基因工程菌的构建。
实施例2：逐级催化制备肝素
(1)发酵生产肝素修饰酶
将实施例1中构建得到的重组菌株GS115/NDST1、GS115/C5 epi、GS115/2-OST、GS115/6-OST、GS115/3-OST分别进行3-L分批补料发酵。
首先分区划线得到单菌落，挑取单菌落接种于5ml YPD液体培养基中，在30℃，220rpm条件下培养16-18h，然后按10％接种量分别转接至三瓶50mL YPD液体培养基中，于30℃220rpm培养24h左右(OD 600为60-70)，然后按15％接种于含有1L发酵培养基的3-L发酵罐中，控制发酵温度为28℃，pH为5.5，通气量为4.0vvm，搅拌转速和溶氧相关联，控制溶氧在30％，搅拌转速在300-1000rpm。待发酵培养基中的甘油被消耗殆尽继续饥饿培养2-3h后，饥饿培养后以恒速流加方式进行50％(v/v)甘油(含12mL/L PTM1)补料10h，补料速率为20mL·h -1·L -1，补料结束后继续饥饿培养2h，进入甲醇诱导阶段，转速不变。用含12mL·L -1PTM1的甲醇流加诱导并且将甲醇终浓度控制在18g/L，甲醇流加速率和培养基中甲醇终浓度由甲醇检测器实时在线控制，诱导108h。收集发酵得到的菌体，用去离子水洗涤菌体两遍后重悬菌体，采用高压匀浆破壁后离心得到胞内上清。
N-磺酸化肝素前体(-GlcA-GlcNS-)(p01)制备的反应体系：反应体系中肝素前体浓度为 1g/L，向其中添加过量NDST1酶液，PAPS终浓度为0.5g/L(过量)，在37℃，pH7.4条件下反应24h。图8和图9表示成功制备含有-GlcA-GlcNS-结构的N-磺酸化肝素前体，转化率为91％。
-IndoA2S-GlcNS-(p02)的制备：反应体系中的N-磺酸化肝素前体(p01)浓度为1g/L，向其中添加过量C5 epi酶液和2-OST酶液，PAPS终浓度为0.5g/L，在37℃，pH7.4条件下反应24h。图10和11表示成功制备得到含有-IndoA2S-GlcNS-的多糖，转化率为87.7％
-IndoA2S-GlcNS6S-(p03)的制备：反应体系中的-IndoA2S-GlcNS-(p02)浓度为1g/L，向其中添加过量6-OST1酶液，PAPS终浓度为0.5g/L，在37℃，pH7.4条件下反应24h。图12表示成功制备得到含-IndoA2S-GlcNS6S-结构的多糖，转化率为91.5％。
3-磺酸化肝素(p04)的制备：反应体系中的-IndoA2S-GlcNS6S-(p03)浓度为1g/L，向其中添加过量3-OST1酶液，PAPS终浓度为0.5g/L，在37℃，pH7.4条件下反应24h。肝素最终产量为0.95g/L，转化率为95％。
实施例3：不同分子量肝素前体的制备
不同分子量肝素前体(图7)制备，酶解肝素前体反应液(10g/L肝素前体)：
肝素前体的分子量通过控制肝素裂解酶I和III的浓度和反应时间来获得，反应体系为在50mmol/L Tris-HCl(pH7.4)缓冲液中进行：终浓度1g/L肝素前体，10μl 4U/L肝素裂解酶I，10μL 4U/mL的肝素裂解酶III，37℃条件下反应。反应结束后检测肝素前体及肝素分子量大小。
结果显示，0min时肝素前体分子量为35kDa，反应15min时肝素前体分子量为15kDa，反应30min时肝素前体分子量为8kDa，反应45min时肝素前体分子量为4kDa，反应60min时肝素前体分子量为2kDa，反应120min时肝素前体分子量为1.4kDa，反应240min时反应120min时肝素前体分子量为1.3kDa，反应360min时肝素前体分子量为1.2kDa，反应480min时肝素前体分子量为1.1kDa。
实施例4：重组大肠杆菌发酵培养获取PAPS合成双功能酶ASAK S和PPK S
本实施例所用PAPS合成双功能酶ASAK S5(Gene为ID:853466，其核苷酸序列如SEQ ID NO.22所示的atpsS基因和GenBank登录号为M74586.1，其核苷酸序列如SEQ ID NO.23所示的apskE基因融合)和PPK S(GeneID登录号为878853，其核苷酸序列如SEQ ID NO.24所示)的表达、纯化及制备根据文献获得(Closed-Loop System Driven by ADP Phosphorylation from Pyrophosphate Affords Equimolar Transformation of ATP to 3’-Phosphoadenosine-5’-phosphosulfate，2021年)。
挑取重组大肠杆菌单菌落于LB培养基中过夜培养，将种子按照2％接种量接种于TB培养基中，继续培养至OD 600为0.6-0.8时进行诱导表达，诱导条件：0.3-0.5mM的IPTG诱导表达(30℃，220rpm)，诱导表达时间为8-12h。然后离心收集菌体，用去离子水洗涤菌体2次后，用50mM Tris-HCl(pH7.5)溶液重悬细胞，然后在800bar条件下高压匀浆破壁5min，离心收集破壁上清液。重组蛋白使用AKTA start 25中的镍亲和层析柱纯化，并使用Hi Trap Desalting脱盐柱进行脱盐处理，分别得到纯化后的ASAK S5和PPK S。
实施例5：一种基于PAPS制备不同分子量肝素的磺酸化修饰体系构建
NDST1、C5 epi、2-OST、6-OST、3-OST由摇瓶培养或发酵罐获得，在制备肝素时，催化反应在50mL 50mmol/L MES(pH7.4)缓冲溶液中进行：5mL 10g/L不同分子量肝素前体、5mL 3500U/L NDST1、5mL 3500U/L C5 epi、5mL 3500U/L 2-OST、5mL 3500U/L 6-OST、5mL 3500U/L 3-OST及终浓度为0.5g/L的PAPS，40℃条件下反应24h，收集反应液。
对于收集得到的反应液的处理方法：向收集得到的反应上清中加4倍预冷的无水乙醇沉淀大分子的多糖和杂质，离心去除沉淀，小分子量的肝素溶解在上清中。将含有乙醇的样品进行冷冻干燥得到产量20g/L，纯度均80％以上的不同分子量的肝素的样品。
实施例6：一种从ATP出发制备不同分子量肝素的磺酸化修饰体系构建
NDST1、C5 epi、2-OST、6-OST、3-OST由摇瓶培养或发酵罐获得，在制备肝素时，催化反应在50mL 50mmol/L MES(pH7.4)缓冲溶液中进行：5mL 10g/L不同分子量肝素前体、5mL 3500U/L NDST1、5mL 3500U/L C5-epi、5mL 3500U/L 2-OST、5mL 3500U/L 6-OST、5mL 3500U/L 3-OST、10μM ASAK S5、0.5g/L PPK S及终浓度为5g/L的ATP，2g/L的MgSO 4，40℃条件下反应48h，收集反应液。
按照实施例5乙醇沉淀法分离与纯化大分子肝素及小分子量肝素，得到不同分子量的肝素。
实施例7：毕赤酵母共培养简化肝素生产工艺
开发一种有效的方法来合成肝素对于理解其生物合成机制也是必不可少的。为提高肝素的合成能力，简化生产工艺，在3-L生物反应器中对共培养体系进行了放大。
一级种子液为将GS115/NDST1、GS115/C5 epi、GS115/2-OST、GS115/6-OST、GS115/3-OST接种至5mL YPD培养基培养16h(OD 600≈6.0)，二级种子液按照10％接种比例接种至500mL摇瓶，之后按照接种比例为NDST1(OD 600≈20)：C5 epi(OD 600≈20)：2OST(OD 600≈20)：6 OST(OD 600≈20)：3OST(OD 600≈20)＝1:1:1:1:1，按照10％接种量接入在3-L生 物反应器(含有毕赤酵母发酵培养基)，并加入终浓度为0.1mM的甲醇诱导，在诱导108h后，收集细胞使用缓冲溶液(50mM MES，pH7.4)重悬细胞并在4℃下使用高压匀浆破碎获得混合酶液。
具体酶催化反应在50mL 50mmol/L MES(pH7.4)缓冲溶液中进行：40℃条件下，将25mL适量的混合酶液加入终浓度0.5g/L PAPS及不同终浓度肝素前体(0.5g/L，0.4g/L，0.3g/L，0.2g/L，0.1g/L)制备不同磺酸化程度的肝素，混合均匀，在40℃条件下充分反应24h。反应结束后，将产物煮沸5min，离心去除杂蛋白，上清使用乙醇沉淀法醇沉两次。使用LC-MS鉴定不同位置磺酸化二糖分布如下表所示：
表2不同位置磺酸化二糖分布
Figure PCTCN2022117166-appb-000004
产物使用HiPrep Q HP 16/10柱纯化。柱体积(CV)：20mL；流速：3mL·min -1；检测波长：210nm；平衡液：浓度0.02mol·L -1的pH8.0磷酸盐缓冲液；洗脱液：含1mol·L -1NaCl的磷酸盐缓冲液；洗脱梯度：0-80mmol·mL -1NaCl，3CV(柱体积)；上样量：100mg肝素产物；分离程序：平衡-上样-清洗(冲洗样品中未与柱子结合的部分)-洗脱-平衡，为一个循环。
实施例8：不同比例毕赤酵母共培养制备不同抗凝血活性的肝素
将实施例7中NDST1：C5 epi：2OST：6 OST：3OST的比例分别替换为2:1:1:1:1，1:2:1:1:1，1:1:2:1:1，1:1:1:2:1，1:1:1:1:2(比例1对应OD 600≈20)，按照上述培养方法在3-L生物反应器培养，按照以下两种方法制备肝素：方法1，将50mL不同的混合酶液加入0.5g/L PAPS及0.1g/L的肝素前体，混合均匀，在40℃条件下充分反应24h方法2，将50mL不同的混合酶液加入10μM ASAK S5、0.5g/L PPK S，终浓度为5g/L的ATP，2g/L的MgSO 4，在40℃条件下充分反应24h，制备得到抗凝血活性的肝素。
实施例9：不同分子量肝素的制备
以实施例3得到的不同分子量(35kDa，15kDa，8kDa，4kDa，2kDa，1.4kDa，1.3kDa，1.2kDa，1.1kDa)的肝素前体，以实施例7中1:1:1:1:1接种比例得到混合酶液在50mL 50mmol/L MES(pH7.4)缓冲溶液中进行以下两种催化反应：
(1)取25mL的混合酶液加入终浓度0.5g/L PAPS及0.1g/L的肝素前体，混合均匀，在40℃条件下充分反应24h，反应后测定产物的分子量，制备得到不同分子量的肝素。
(2)取25mL的混合酶液，加入10μM ASAK S5、0.5g/L PPK S，终浓度为5g/L的ATP，2g/L的MgSO 4，在40℃条件下充分反应24h，反应后测定产物的分子量，制备得到不同分子量的肝素。
表3不同分子量肝素前体制备得到不同分子量肝素
Figure PCTCN2022117166-appb-000005
实施例10：肝素的LC-MS检测
取500μl实施例6制备得到的肝素样品，加入10μl 4U/L肝素裂解酶I和4U/L肝素裂解酶III，置于37℃水浴锅中处理10h。将裂解后的溶液置于90℃加热10min使蛋白失活变性，离心后取上清进行LC-MS检测。LC-MS检测使用HILIC色谱柱(3μm，2.0×150mm，YMC,Japan)。洗脱液A为超纯水，洗脱液B为乙腈。所用的洗脱梯度设定如下：0-2分钟，90％B；2-8分钟，90-50％B；8-12分钟，50％B；12-13分钟，90％B。柱温保持在35℃，流速为0.2mL/min。在负离子模式下对m/z 100-800的质量范围进行扫描监测。
肝素的二糖分子在负离子模式下质荷比应含有以下离子流：m/z：378.3，m/z：416.3，m/z：496.4，m/z：458.05，m/z：577.6。如图8、图9，图10，图11，图12所示的质谱结果可以看出本实施例实现了不同分子量肝素的合成。
实施例11：肝素的抗凝血活性测定
将实施例5中0.5g/L，0.4g/L，0.3g/L，0.2g/L，0.1g/L浓度肝素前体及按不同比例重组菌 制备得到的生物工程肝素测定其抗凝血活性。
首先应用含有1mg/mL牛血清白蛋白(BSA)的PBS将FXa因子和human ATIII分别稀释至60nM和0.65pM。显色底物S-2765和S-2238溶于水制备成1mg/mL原液。测试用的寡糖用PBS稀释成浓度为200nM。首先将60μL ATIII和15μL上述肝素溶液涡旋混匀，室温条件下孵肓2min。然后加入90μL FXa溶液，室温条件下孵育4min，最后分别加入30μL显色底物S-2765和S-2238。在405nm条件下测量反应混合物的吸光度，将不同的样品浓度对初始反应速率作图计算测试寡糖的IC50。
实施例5中0.5g/L，0.4g/L，0.3g/L，0.2g/L，0.1g/L浓度肝素前体及按1:1:1:1:1比例重组菌制备得到的生物工程肝素采用体外比色法评价的抗FXa因子和抗FIIa因子活性(左侧柱子表示抗FXa因子活性，右侧柱子表示抗IIa因子活性)。如图13所示，添加0.1g/L肝素前体获得的肝素抗Fxa活性为79.94ng/mL，抗IIa活性为37.07ng/mL，与Sango生物技术(上海)的肝素相似(图13 Heparin)，但高于其他生物工程肝素，抗Fxa/抗FIIa比值(2.16±0.31)。
如图14和15所示，不同接种比例按照实施例9的方法一和方法二获得的肝素具有不同的抗凝血活性，其中，1:1:1:2:1接种比例得到的肝素抗凝血活性：方法一获得的肝素抗Fxa活性为86.61ng/mL，抗IIa活性为54.53ng/mL，抗Fxa/抗IIa比值(1.59±0.24)，方法二抗Fxa活性为79.62ng/mL，抗IIa活性为40.85ng/mL，抗Fxa/抗IIa比值(1.95±0.27)；1:1:1:1:2接种比例得到的肝素抗凝血活性结果：方法一获得的肝素抗Fxa活性为88.74ng/mL，抗IIa活性为50.46ng/mL，抗Fxa/抗IIa比值(1.76±0.31)方法二抗Fxa活性为89.53ng/mL，抗IIa活性为54.47ng/mL，抗Fxa/抗IIa比值(1.64±0.29)。因此，本发明所提供的体外全酶法在生物活性肝素的生产中具有很大的潜力。
虽然本发明已以较佳实施例公开如上，但其并非用以限定本发明，任何熟悉此技术的人，在不脱离本发明的精神和范围内，都可做各种的改动与修饰，因此本发明的保护范围应该以权利要求书所界定的为准。

Claims (8)

  1. 一种对肝素前体磺酸化修饰的方法，其特征在于，在含有肝素前体的体系中，加入PAPS和肝素修饰酶进行反应；所述肝素修饰酶为N－脱乙酰/N－磺酸转移酶、葡萄糖醛酸C5-变构酶、磺酸乙酰肝素2-磺酸转移酶、磺酸乙酰肝素6-磺酸转移酶和磺酸乙酰肝素3-磺酸转移酶，所述N－脱乙酰/N－磺酸转移酶来源于Homo sapiens；所述葡萄糖醛酸C5-变构酶来源于Homo sapiens；所述磺酸乙酰肝素2-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素6-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素3-磺酸转移酶来源于Mus musculus。
  2. 根据权利要求1所述的方法，其特征在于，将所述肝素修饰酶同时或逐级添加至反应体系中。
  3. 一种制备不同分子量肝素的方法，其特征在于，所述方法为(a)或(b)所述任一：
    (a)以不同分子量的肝素前体为底物，加入PAPS和肝素修饰酶反应，生成得到不同分子量的肝素；
    (b)在含有ATP的体系中，加入PAPS合成双功能酶和聚磷酸激酶PPK S，加入肝素修饰酶反应，生成得到不同分子量的肝素；
    所述肝素修饰酶为N－脱乙酰/N－磺酸转移酶、葡萄糖醛酸C5-变构酶、磺酸乙酰肝素2-磺酸转移酶、磺酸乙酰肝素6-磺酸转移酶和磺酸乙酰肝素3-磺酸转移酶，所述N－脱乙酰/N－磺酸转移酶来源于Homo sapiens；所述葡萄糖醛酸C5-变构酶来源于Homo sapiens；所述磺酸乙酰肝素2-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素6-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素3-磺酸转移酶来源于Mus musculus。
  4. 根据权利要求3所述的方法，其特征在于，将所述肝素修饰酶分别添加至反应体系中，或以混合粗酶液的形式加入反应体系。
  5. 根据权利要求4所述的方法，其特征在于，所述混合粗酶液，是利用重组毕赤酵母按比例接种，发酵得到的；所述重组毕赤酵母为分别表达N－脱乙酰/N－磺酸转移酶、葡萄糖醛酸C5-变构酶、磺酸乙酰肝素2-磺酸转移酶、磺酸乙酰肝素6-磺酸转移酶和磺酸乙酰肝素3-磺酸转移酶的重组毕赤酵母，所述重组菌按菌浓＝(1～2):(1～2):(1～2):(1～2):(1～2)的比例混合，加入毕赤酵母发酵培养基发酵得到。
  6. 根据权利要求5所述的方法，其特征在于，所述重组菌以毕赤酵母GS115为处出发菌株。
  7. 根据权利要求6所述的方法，其特征在于，所述肝素前体是由E.coli strain Nissle 1917或E.coli K5发酵得到，再按不低于4 U/g肝素前体的量加入肝素裂解酶，反应0～8h，得到不同分子量的肝素前体。
  8. 一种酶法制备肝素的方法，其特征在于，所述方法是向在含有肝素前体的反应体系中，加入PAPS和肝素修饰酶，在35～45℃下反应20～25h，制备得到肝素；或是在含有ATP的体系中，加入PAPS合成双功能酶和聚磷酸激酶PPK S，再加入肝素修饰酶反应，制备得到肝素，所述肝素修饰酶为N－脱乙酰/N－磺酸转移酶、葡萄糖醛酸C5-变构酶、磺酸乙酰肝素2-磺酸转移酶、磺酸乙酰肝素6-磺酸转移酶和磺酸乙酰肝素3-磺酸转移酶；所述N－脱乙酰/N－磺酸转移酶来源于Homo sapiens；所述葡萄糖醛酸C5-变构酶来源于Homo sapiens；所述磺酸乙酰肝素2-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素6-磺酸转移酶来源于Gallus；所述磺酸乙酰肝素3-磺酸转移酶来源于Mus musculus。
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