CN110016471B

CN110016471B - Recombinant ancrod enzyme, industrial scale preparation and purification method and composition thereof

Info

Publication number: CN110016471B
Application number: CN201910286716.5A
Authority: CN
Inventors: 孙雷; 王增博
Original assignee: Beijing Bokangning Biomedicine Technology Co ltd
Current assignee: Beijing Bokangning Biomedicine Technology Co ltd
Priority date: 2019-04-10
Filing date: 2019-04-10
Publication date: 2020-10-02
Anticipated expiration: 2039-04-10
Also published as: CN110016471A

Abstract

Relates to recombinant ancrod enzymes, methods of industrial scale preparation and purification, and compositions thereof. Specifically, the recombinant ancrod enzyme has an amino acid sequence single chain shown in the specification, and is glycoprotein with the average molecular weight of 39-41 KDa, the molecular weight range of 33-52 KDa and the modified sugar content of more than 19%. It also relates to the preparation and purification of the recombinant ancrod enzymes, and their compositions in the form of injection solutions. The recombinant ancrod enzyme of the invention has obviously better performance than natural ancrod enzyme. The method can obtain the recombinant ancrod enzyme with high expression quantity according to the industrial production specification, the yield can reach more than 200IU/ml of fermentation liquor per milliliter, and the specific activity can reach 1000 IU/mg. The recombinant ancrod enzyme has more complex and complete glycosylation level, obviously enhances the stability, and solves the problems of low expression level and difficult industrialization of the ancrod enzyme. The obtained injection composition exhibits excellent pharmaceutical properties.

Description

Recombinant ancrod enzyme, industrial scale preparation and purification method and composition thereof

Technical Field

The invention relates to a recombinant ancrod enzyme, a preparation method and application thereof, and a pharmaceutical composition containing the recombinant ancrod enzyme and the application thereof. More specifically, the invention relates to a method for preparing recombinant protein by adopting a genetic engineering technology and utilizing a mammalian CHO cell culture production method, and then through a purification process, the recombinant ancrod enzyme with high expression quantity can be easily obtained according to an industrial production specification, the yield can reach more than 200IU/ml of fermentation liquor per milliliter, and the specific activity can reach 1000 IU/mg. The recombinant ancrod enzyme obtained by the invention has more complex and complete glycosylation level, the stability is obviously enhanced, the problems of low expression level and difficult industrialization of the existing products are solved, and the invention also relates to the application of the recombinant ancrod enzyme in treating acute cerebral infarction.

Background

Ankeluose (Ancrod) is specifically selected from Malayan pit viper (Malayan pit viper, Callosesasmarshorostom)a) The specific action substrate of snake venom thrombin-like enzyme is fibrinogen, unlike thrombin, which cleaves only the α chain of fibrinogen but not the β chain, when it hydrolyzes Arg in the plasma fibrinogen α chain¹⁶the-GLy bond can release fibrinopeptide A, thereby rapidly converting fibrinogen in blood into fibrin, and since the thrombin-like enzyme of snake venom does not activate coagulation factor XIII, the generated fibrin monomer is not cross-linked to form a firm fibrin network structure, and is easily hydrolyzed by in vivo fibrinolytic enzyme, thereby inhibiting thrombosis, and having the effects of reducing blood viscosity, inhibiting erythrocyte agglutination and sedimentation, enhancing the vascular permeability and deformability of erythrocyte, reducing vascular resistance, and improving microcirculation. The thrombolytic effect is rapid, and the function of the ischemic part is recovered, thereby achieving the effects of treating and preventing relapse.

The snake venom thrombin-like enzyme preparations are marketed in the following varieties: ancrod (Ancrod, Viprinex, Arwin) from venom of Pallas pit Viper in Malaysia; batroxobin (Batroxobin) from venom of Bothrops moojeni (Bothrops moojeni); defibrase (Defibrase) derived from venom of Agkistrodon acutus (Agkistrodon acutus). In 1985 to 2000, multi-component preparations containing snake venom thrombin with different snake venom sources are circulated in China, and most of the preparations are named as pit viper antithrombotic enzymes. Since 1997, domestic defibrase replaced pit viper antithrombotic enzyme.

The natural snake venom thrombin is glycoprotein, and the glycosylation level is positively correlated with the specific activity and the activity stability.

Because the agkistrodon halys are listed in China as secondary endangered protected animals, the natural snake venom resources are extremely limited, so that the expression of the snake venom thrombin-like enzyme by adopting a genetic engineering technology has practical significance. The Japanese scholars successfully expressed batroxobin gene in Escherichia coli at the earliest time in 1987 (J.biol.chem.262: 3132-.

The Amino acid sequence of the natural Ancrod enzyme was reported in detail in its research paper by the American scholars William Burkhart et al (William Burkhart, et al, Amino acid sequence determination of isoccrod, the same-like alpha-fibrinogenase from the vehicle of Akistrodon rhotoma, Federation of European Biochemical Societies, 1992, Vol 297(3):297-301) as early as 1992, a glycoprotein containing 234 Amino acids. The 234 amino acid sequences of this protein are described in the William Burkhart reference and are included in the global protein resource library known in the art, http:// www.uniprot.org, see in particular the information described in the library website http:// www.uniprot.org/uniprot/P26324. The naturally occurring Ancrod consisting of 234 amino acids, which is purified from Akistrrodon rhodostoma venom, is extremely difficult to industrially produce on a stable scale the natural Ancrod to be used clinically successfully in a safe, effective and controllable form due to well-known factors such as the growth environment of the snake, age of the snake, season of virus collection, etc., which are related to the variation of snake venom raw materials, and the influence of impurities in the snake venom and the limitation of the yield of raw materials.

The applicant's published invention patent application 2018104523815 discloses stable methods for obtaining high expression levels of ancrod, particularly recombinant ancrod, on an industrial scale, however these methods are still subject to considerable improvement.

Therefore, there is still a need in the art for a method for producing ancrod enzymes, particularly a method for stably obtaining ancrod enzymes, particularly recombinant ancrod enzymes, in high expression levels on an industrial production scale.

Disclosure of Invention

The invention aims to provide a recombinant ancrod enzyme, a preparation method and application thereof, in particular to a method for stably obtaining the recombinant ancrod enzyme with high expression quantity in industrial production scale. The recombinant protein has more complex and complete glycosylation level, and solves the problem that the existing products have low expression level and are difficult to industrialize. The invention also aims to provide the application of the recombinant ancrod enzyme in treating acute cerebral infarction. The recombinant ancrod enzyme has stronger in vitro activity and higher stability.

In a first aspect of the present invention, there is provided a recombinant ancrod enzyme which is a single-chain of 234 amino acid residues, N-terminal and C-terminal amino acid residues of valine (V) and proline (P), respectively, having the following sequence:

VIGGDECNIN EHRFLVAVYE GTNWTFICGG VLIHPEWVIT AEHCARRRMN

LVFGMHRKSE KFDDEQERYP KKRYFIRCNK TRTSWDEDIM LIRLNKPVNN

SEHIAPLSLP SNPPIVGSDC RVMGWGSINR RIDVLSDEPR CANINLHNFT

MCHGLFRKMP KKGRVLCAGD LRGRRDSCNS DSGGPLICNE ELHGIVARGP

NPCAQPNKPA LYTSIYDYRD WVNNVIAGNA TCSP。

the recombinant ancrod enzyme is glycoprotein with the average molecular weight of 39-41 KDa, and comprises 5N-Link glycosylation binding sites which are respectively positioned at Asn²³-Trp²⁴-Thr²⁵，Asn⁷⁹-Lys⁸⁰-Thr⁸¹，Asn⁹⁹-Asn¹⁰⁰-Ser¹⁰¹，Asn¹⁴⁸-Phe¹⁴⁹-Thr¹⁵⁰And Asn²²⁹-Ala²³⁰-Thr²³¹At asparagine residue, and the isoelectric point of the glycoprotein is 4.5-5.5.

The recombinant ancrod enzyme is glycoprotein with a molecular weight distribution range of 33-52 KDa.

The recombinant ancrod enzyme is a glycoprotein with a modified sugar content of 19-49%. As a result of detailed analysis, it has been known that modified saccharides attached to glycosylation sites include galactose, trehalose, sialic acid, and the like, and their bonding pattern on amino acid chains shows a multi-layered antenna-like structure.

The molecular weight of the single-chain ancrod enzyme consisting of 234 amino acid residues is 26570 Da; the recombinant ancrod glycoprotein prepared by the method is determined by a liquid chromatography-mass spectrometry (LC-MS), and has an average molecular weight of 39-41 kDa and a molecular weight distribution range of 33-52 kDa (the distribution span reaches more than 17 kDa). In addition, the inventor refers to a method for obtaining natural ancrod glycoprotein shown in Lane 3 of A of William Burkhart document Fig.1, adopts rhodostomin malaysia as a raw material to obtain natural glycosylated protein, namely natural ancrod, and the average molecular weight of the natural ancrod glycoprotein is 37.5-38 kDa and the molecular weight distribution range is 32-41 kDa (the distribution span is about 9kDa) through the LC-MS method measurement/calculation of the invention; the reason for the difference between the results of the LC-MS measurements and those shown in the William Burkhart reference is the difference in the detection method employed, which is a relatively accurate result that can be achieved under the current technical conditions. Therefore, the recombinant ancrod glycoprotein prepared by the invention has the same single-chain of ancrod enzyme consisting of 234 amino acid residues as that of natural ancrod enzyme, but has more complex and complete glycosylation level (probably caused by different amounts of the accessed sugar and different structures/modes of accessing) due to different glycosylation modified sugar connected on the single-chain of amino acid residues, and can show remarkably enhanced stability and biological activity compared with the natural protein, so that the recombinant ancrod glycoprotein prepared by the invention is essentially completely different from the natural ancrod enzyme. The complexity and completeness of ancrod glycosylation can be reflected in the molecular weight and distribution of glycoproteins: the larger the molecular weight is, the higher the glycosylation degree is, the higher the complexity of glycosylation branches and side chains is, and the higher the stability and biological activity of the corresponding glycoprotein are; the higher stability of the glycoprotein enables the production of the glycoprotein in high yields and high expression levels on an industrial scale. In the present invention, the molecular weight concerned and parameters related thereto such as molecular weight distribution range, average molecular weight and the like are measured and calculated by liquid chromatography-mass spectrometry (LC-MS) or measured and calculated by mass spectrometry, unless otherwise specified.

Further, the second aspect of the present invention provides a method for preparing a recombinant ancrod enzyme, comprising the steps of:

(1) constructing a gene expression vector and a recombinant plasmid for coding the recombinant ancrod enzyme:

construction of vectors for secretory expression of recombinant proteins in mammalian cells (e.g., ATK-V03-aSP vector, which is a conventional gene expression vector, known to those skilled in the art, and commercially available, ATK-V03-aSP vector commercially available in one embodiment of the present invention, which is constructed by AutekBio in one example, and in one embodiment, the ATK-V03-aSP vector contains a CMV promoter, a BGH pA tailing signal, and a Neo selection marker gene for selecting stably expressing cells in eukaryotic cells, and in one embodiment, the ATK-V03-aSP vector also contains a replication initiation site derived from pMB1 and an ampicillin resistance gene, which can be selected and replicated in E. coli), and constructing an Ancrod recombinant plasmid (e.g., ATK-V03-aSP-Ancrod, e.g., commercially constructed);

(2) stable expression of recombinant ancrod in mammalian host cells:

transfecting an expression vector containing ancrod protein to a mammalian host cell, and screening a cell strain for stably expressing a target protein;

(3) cell culture production of recombinant ancrod:

transferring the screened stable cell strain into a reaction tank for large-scale culture, and harvesting the culture when the cell density reaches the maximum.

In general, in this step, CHO (ATK-CHO-SX) cultured in suspension in serum-free medium (SFM) was used as the host cell under the conditions of 37 ℃ and 5% CO₂120rpm (in the present invention, the cell doubling time (PDT) is about 17 hours per 2-3 days of subculture under these conditions; the maximum viable cell density can reach 1 × 10 in batch culture⁷Individual cells/mL);

(4) purifying the recombinant ancrod enzyme:

(41) pretreatment before column chromatography: filtering the culture solution containing the recombinant ancrod enzyme obtained in the previous step to remove cell debris, collecting filtrate, then performing ultrafiltration concentration, and performing ultrafiltration on the filtrate by using a 30KDa cut-off molecular weight membrane plate to 1/8-1/10 of the original volume;

(42) affinity chromatography column: purifying by using an affinity chromatography column (for example, in one embodiment of the invention, the method adopts a Heparin Sepharose Fast Flow, GE), eluting and collecting active components by using an elution condition of NaCl with the salt concentration of 0.1-0.4 mol/L and Tris-HCl with the salt concentration of 0.05mol/L and pH7.0-7.5 buffer solution;

(43) and (3) reversed-phase liquid chromatography purification: purifying the obtained recombinant ancrod protein by adopting a preparative reverse phase liquid chromatography technology, and further removing other impurities by utilizing the difference of polarity and adopting an ethanol-water system gradient elution method;

(44) affinity column chromatography: the recombinant protein collected in the previous step is purified using an affinity chromatography column ((e.g., in one embodiment of the present invention, Heparin Sepharose Fast Flow, GE), ethanol is removed and concentration of the recombinant protein is achieved.

The process according to the second aspect of the invention, wherein in step (43) a C4 preparative chromatography column is used, eluting with a gradient as shown in the following table:

time/min	A	B
				0～50	90→30	10→70
50～60	30	70
			61.～71	90	10

Wherein the mobile phase A is phosphoric acid water solution with pH2.3, the mobile phase B is ethanol, the detection wavelength is 214nm, and the elution flow rate is 20 mL/min. In one embodiment, 1% propylene glycol is additionally added to both mobile phase a and mobile phase B.

The method according to the second aspect of the present invention, wherein the affinity column chromatography in step (44) is performed under the same conditions as those in step (42).

The method according to the second aspect of the present invention, wherein in the step (1), the step of constructing a gene expression vector encoding the recombinant ancrod further comprises: the chemical synthesis method completes the DNA coding sequence of Ancrod glycoprotein, the synthesized DNA coding sequence is connected into ATK-V03-aSP vector by T4DNA ligase to obtain gene recombination expression plasmid ATK-V03-aSP-Ancrod, and the correctness of the insertion sequence in the recombination plasmid is verified by DNA sequencing.

The method according to the second aspect of the present invention, wherein said mammalian cell expression vector is ATK-V03-aSP.

The method according to the second aspect of the present invention, wherein the transfection method in step (2) is an electroporation transfection method (electroporation) of cells.

The method according to the second aspect of the present invention, wherein said mammalian host cell is selected from the group consisting of: CHO (Chinese hamster Ovary cells), HEK293, BHK, NS0, and Sp2/0 cells. Preferably a CHO cell; more preferably, the DHFR enzyme-deficient CHO-suspension cells (DHFR-CHO) have been acclimatized to suspension growth in serum-free medium.

The method according to the second aspect of the present invention, wherein in step (3), the composition of the serum-free medium (SFM) is: glucose 0.6%, glutamine 2mM, NaHCO 33 mM, Hepes 5mM, insulin 2.5. mu.g/ml, transferrin 100ng/ml, butanediamine 60. mu.M, sodium selenate 30nM, penicillin 50. mu.g/ml, streptomycin 50. mu.g/ml, DF12 to 100 ml.

According to the method of the second aspect of the invention, the step of producing recombinant ancrod by cell culture in step (3) is to transfer the stable cell strains screened previously into a cell reaction tank for large-scale culture, in particular to obtain a cell culture solution with high expression of recombinant ancrod by optimizing the cell culture conditions⁷At maximum density of individuals/mL, the temperature was lowered from 37 ℃ to 33 ℃ and the cells were incubated at this temperature until no further increase in expression yield occurred (maximum cell density reached 1 × 10⁷At 37 ℃ did not contribute to the further increase in yield, but it was found that, at this maximum density, lowering the culture temperature to 37 ℃ to 33 ℃ continued to increase the yield to a level of about 1.8 fold increase in cell density to about 2.8 × 10⁷More than one/mL). The method can improve the activity level of the expressed protein and the cumulative yield of the recombinant protein. Therefore, in one embodiment of the present invention, in step (3), when the cell density is maximized, the temperature is decreased from 37 ℃ to 33 ℃ and the culture is continued until the cell density is not increased any more.

In another embodiment, the method for optimizing cell culture conditions further comprises supplementing the basic culture medium, namely serum-free culture medium, with special additives, preferably, adding 100. mu. M, N-acetyl-D-amino mannose (Mannac)2mM copper chloride and 50. mu.M potassium pyrophosphate to the serum-free culture medium. The method can obviously increase the glycosylation degree of the recombinant ancrod enzyme, and obviously increase the complexity of glycosylation branches, side chains and the like. Thus, in one embodiment of the present invention, the serum-free medium used in step (3) was supplemented with copper chloride 100. mu. M, N-acetyl-D-aminommannose 2mM, potassium pyrophosphate 50. mu.M. In the methodology investigation test, the invention discovers that when any one or two or all three of the three are supplemented into the serum-free culture medium, the glycosylation degree and the complexity of the recombinant ancrod enzyme cannot be effectively increased, and only when the three are simultaneously increased by the amount, the glycosylation degree and the complexity of the recombinant ancrod enzyme can be effectively increased, so that the performance of the glycoprotein is improved.

The method according to the second aspect of the present invention, wherein the method of step (3) is: the selected stable cell line was transferred to a reaction tank, and a serum-free medium supplemented with copper chloride 100. mu. M, N-acetyl-D-aminommannose (Mannac)2mM and potassium pyrophosphate 50. mu.M was used under a culture condition of 37 ℃ and 5% CO₂Culturing at 120rpm until the cell density is not increased, then reducing the culture temperature from 37 ℃ to 33 ℃ and continuing culturing until the cell density is not increased, and then harvesting the culture.

In the step (4) of the method, the recombinant ancrod enzyme is purified and prepared by adopting a specific chromatography in the purification and preparation step of the recombinant ancrod enzyme, the chromatography is simple in process, easy to amplify and produce, mild in condition, high in stability and high in activity, and the purity of the obtained recombinant ancrod enzyme reaches more than 98.5%.

Further, the third aspect of the invention provides the application of the recombinant ancrod enzyme in treating acute cerebral infarction diseases. For example, for acute cerebral infarction and for ameliorating various occlusive vascular diseases.

Further, the fourth aspect of the present invention provides a method for cell culture in the production of recombinant ancrod, comprising the steps of:

transferring the screened stable cell strain into a reaction tank for large-scale culture, and harvesting the culture when the cell density reaches the maximum. In general, in this step, CHO (ATK-CHO-SX) cultured in suspension in serum-free medium (SFM) was used as the host cell under the conditions of 37 ℃ and 5% CO₂120rpm (in the present invention, the cell doubling time (PDT) is about 17 hours per 2-3 days of subculture under these conditions; the maximum viable cell density can reach 1 × 10 in batch culture⁷Individual cells/mL);

the method according to the fourth aspect of the invention, wherein the serum-free medium (SFM) has the composition: glucose 0.6%, glutamine 2mM, NaHCO 33 mM, Hepes 5mM, insulin 2.5. mu.g/ml, transferrin 100ng/ml, butanediamine 60. mu.M, sodium selenate 30nM, penicillin 50. mu.g/ml, streptomycin 50. mu.g/ml, DF12 to 100 ml.

According to the fourth aspect of the present invention, the method comprises the steps of transferring the stable cell strains selected in the previous step into a cell reaction tank for large-scale culture, particularly, obtaining a cell culture solution of the recombinant ancrod with high expression through optimizing the cell culture conditions⁷At maximum density of individuals/mL, the temperature was lowered from 37 ℃ to 33 ℃ and the cells were incubated at this temperature until no further increase in expression yield occurred (maximum cell density reached 1 × 10⁷At 37 ℃ did not contribute to the further increase in yield, but it was found that, at this maximum density, lowering the culture temperature to 37 ℃ to 33 ℃ continued to increase the yield to a level of about 1.8 fold increase in cell density to about 2.8 × 10⁷More than one/mL). The method can improve the activity level of the expressed protein and the cumulative yield of the recombinant protein. Therefore, in one embodiment of the present invention, in step (3), when the cell density is maximized, the temperature is decreased from 37 ℃ to 33 ℃ and the culture is continued until the cell density is not increased any more.

The method according to the fourth aspect of the present invention, wherein said optimization of cell culture conditions further comprises supplementing the basal medium, i.e., serum-free medium, with specific additives, preferably, further adding copper chloride 100. mu. M, N-acetyl-D-aminommannose (Mannac)2mM, potassium pyrophosphate 50. mu.M to the serum-free medium. The method can obviously increase the glycosylation degree of the recombinant ancrod enzyme, and obviously increase the complexity of glycosylation branches, side chains and the like. Thus, in one embodiment of the present invention, the serum-free medium used in step (3) was supplemented with copper chloride 100. mu. M, N-acetyl-D-aminommannose 2mM, potassium pyrophosphate 50. mu.M. In the methodology investigation test, the invention discovers that when any one or two or all three of the three are supplemented into the serum-free culture medium, the glycosylation degree and the complexity of the recombinant ancrod enzyme cannot be effectively increased, and only when the three are simultaneously increased by the amount, the glycosylation degree and the complexity of the recombinant ancrod enzyme can be effectively increased, so that the performance of the glycoprotein is improved.

The method according to the fourth aspect of the invention comprises the steps of: the selected stable cell line was transferred to a reaction tank, and a serum-free medium supplemented with copper chloride 100. mu. M, N-acetyl-D-aminommannose (Mannac)2mM and potassium pyrophosphate 50. mu.M was used under a culture condition of 37 ℃ and 5% CO₂Culturing at 120rpm until the cell density is not increased, then reducing the culture temperature from 37 ℃ to 33 ℃ and continuing culturing until the cell density is not increased, and then harvesting the culture.

Further, the fifth aspect of the present invention provides a method for purifying recombinant ancrod enzyme, comprising the steps of:

The method according to the fifth aspect of the present invention, wherein in step (43), a C4 preparative chromatography column was used, eluting with the gradient shown in the following table:

time/min	A	B
				0～50	90→30	10→70
50～60	30	70
			61.～71	90	10

The method according to the fifth aspect of the present invention, wherein the affinity column chromatography in step (44) is performed under the same conditions as those in step (42).

Further, the sixth aspect of the present invention provides a method for purifying recombinant ancrod, which comprises purifying the obtained recombinant ancrod protein by reverse phase liquid chromatography, followed by Heparin Sepharose 6FastFlow gel affinity column chromatography in the following manner:

chromatography column (column diameter 50mm, length 12cm), packed with Heparin Sepharose6Fast Flow, PBS-LYS buffer containing: 0.2% sodium chloride, 0.1% L-lysine hydrochloride, 15mmol/L sodium dihydrogen phosphate and sodium hydroxide to adjust pH to 6.8, and water to full volume, wherein the sample is the main active peak in step (3), and is diluted to 1000mL with PBS-LYS buffer solution, and the column flow rate is 2 mL/min. After loading, the sample was equilibrated to baseline with PBS-LYS buffer, eluted with PBS-LYS buffer, and the active fractions were collected. Eluting with PBS-LYS buffer solution to remove impurity components, washing the column with PBS-LYS buffer solution for 1000ml, and regenerating to obtain recombinant ancrod enzyme stock solution.

According to a sixth aspect of the present invention, there is provided a method for purifying recombinant ancrod enzyme, comprising the steps of:

(41) pretreatment before column chromatography: filtering the culture solution containing the recombinant ancrod to remove cell debris, collecting filtrate, then performing ultrafiltration concentration, and performing ultrafiltration by using a 30KDa cut-off molecular weight membrane plate to 1/8-1/10 of the original volume;

(42) affinity chromatography column: purifying by adopting an affinity chromatography column, eluting and collecting active components by using the elution conditions of NaCl with the salt concentration of 0.1-0.4 mol/L and Tris-HCl with the salt concentration of 0.05mol/L and pH7.0-7.5 buffer solution;

(44) affinity column chromatography: purifying the recombinant protein collected in the last step by adopting an affinity chromatography column, removing ethanol and realizing the concentration of the recombinant protein,

wherein the operation of step (44) is as follows:

According to the method of the sixth aspect of the present invention, in the above step (43), a C4 preparative chromatography column was used, eluting with a gradient as shown in the following table:

time/min	A	B
				0～50	90→30	10→70
50～60	30	70
			61.～71	90	10

Wherein the mobile phase A is a phosphoric acid aqueous solution with pH2.3, the mobile phase B is ethanol, the detection wavelength is 214nm, and the elution flow rate is 20 mL/min; for example, 1% propylene glycol is additionally added to both the mobile phase a and the mobile phase B.

Further, the seventh aspect of the present invention provides a method for preparing a recombinant ancrod injection, comprising the steps of:

(a) providing a purified recombinant ancrod stock (optionally determining the titer of the stock);

(b) diluting with PBS-LYS buffer (e.g. to titer 20IU/mL), sterilizing with 0.22um microporous membrane filter, (e.g. 1mL per vial), packaging into ampoules, and sealing by melting to obtain injection.

According to the method of the seventh aspect of the invention, the purified recombinant ancrod enzyme stock solution is prepared by the following method:

wherein the operation of step (44) is as follows:

According to a seventh aspect of the invention, in step (43) above, a C4 preparative chromatography column was used, eluting with a gradient as shown in the following table:

time/min	A	B
				0～50	90→30	10→70
50～60	30	70
			61.～71	90	10

In the above-described steps of the preparation method of the present invention, although the specific steps described therein are distinguished in some detail or in language description from the steps described in the preparation examples of the detailed embodiments below, those skilled in the art can fully summarize the above-described method steps in light of the detailed disclosure throughout the present disclosure.

Any embodiment of any aspect of the invention may be combined with any other embodiment of the invention, as long as they do not contradict. Furthermore, in any embodiment of any aspect of the invention, any feature may be applicable to that feature in any other embodiment of the invention, provided that they do not contradict.

The invention is further described below.

All documents cited herein are incorporated by reference in their entirety and to the extent such documents do not conform to the meaning of the present invention, the present invention shall control. Further, the various terms and phrases used herein have the ordinary meaning as is known to those skilled in the art, and even though such terms and phrases are intended to be described or explained in greater detail herein, reference is made to the term and phrase as being inconsistent with the known meaning and meaning as is accorded to such meaning throughout this disclosure.

In the present invention, the term "molecular weight distribution range" refers to the range from the minimum molecular weight to the maximum molecular weight of the glycoprotein when determining the molecular weight by mass spectrometry, for example, in the mass spectrum of fig. 8 of the present invention, the range from the molecular weight corresponding to the start position of the main peak (33980Da) to the molecular weight corresponding to the end position of the main peak (51840 Da). Similarly, reference to the term "distribution span" refers to the difference between the large end and the small end of the molecular weight distribution range.

The invention adopts large-scale culture conditions and a purification method, the glycosylation of the obtained recombinant ancrod enzyme is more complex and more complete, the activity enhancement stability is improved, the curative effect of resisting acute cerebral infarction in an animal body is obvious, and the safety evaluation result shows that the recombinant protein has no influence on the heart, the respiratory system and the circulatory system, thereby having good clinical application prospect.

The recombinant ancrod is glycoprotein expressed by ancrod gene in CHO cell by gene engineering technology, and has active center of serine and thrombin-like enzyme activity. The average molecular weight is 39K-41kDa by mass spectrum analysis, and the carbohydrate content is about 19-49 percent.

As is known, products extracted from natural snake venom may have unpredictable impurities, so that antigenicity is generated, the production quality is uncontrollable, and in comparison, recombinant proteins have incomparable advantages in the aspects of purity, quality controllability, antigenicity, safety and the like and show wide medical prospects, but recombinant ancrod medicines are not available in the market at home and abroad so far.

The recombinant ancrod enzyme obtained by using gene recombination technology becomes a better choice, and the existing prokaryotic cells (such as escherichia coli) and yeast cell expression systems cannot realize industrialization for preparing recombinant glycoprotein with in vivo activity, and only recombinant protein expressed in mammalian host cells can realize complete glycosylation, in fact, the glycosylation degree of protein is closely related to the functions of in vivo activity, half-life period and the like of the protein, and the glycosylation level of the recombinant protein depends on cell culture conditions and purification processes.

In mammalian cell expression systems, chinese hamster ovary cells (CHO cells) are currently the most suitable host cells for industrial production. Products expressed by CHO cells such as recombinant human erythropoietin injection, recombinant hepatitis B vaccine (CHO cells), recombinant human thrombopoietin injection and recombinant human prourokinase for injection have been used clinically.

The recombinant ancrod prepared by the method of the invention has the following characteristics:

(1) through mass spectrometry, the average molecular weight of the recombinant ancrod enzyme is 39-41 Kda; (2) the recombinant ancrod enzyme contains 19-49% of sugar; (3) the recombinant ancrod enzyme contains 5N-linked glycosylation sites and is complex in glycoform.

Drawings

FIG. 1: ATK-V03-aSP-Antcrod plasmid map.

FIG. 2: clone CIA8-64-33-95 was cultured in a batch process (cell growth; vc-viable cell density, via-cell viability) in a 10 liter bioreactor.

FIG. 3: a batch culture process (target protein expression) of clone CIA8-64-33-95 in a 10 liter bioreactor.

FIG. 4: clone CIA8-64-33-95 was cultured in 50L bioreactor in batch process (cell growth; vc-viable cell density, via-cell viability).

FIG. 5: the batch culture process (target protein expression) of clone CIA8-64-33-95 in a 50L bioreactor.

FIG. 6: first step Heparin Sepharose6Fast Flow gel affinity column chromatography chromatogram.

FIG. 7: and a second step of purifying the chromatogram by reversed phase liquid chromatography.

FIG. 8: LC-MS diagram of recombinant ancrod glycoprotein.

Detailed Description

The present invention will be further described by the following examples, however, the scope of the present invention is not limited to the following examples. It will be understood by those skilled in the art that various changes and modifications may be made to the invention without departing from the spirit and scope of the invention. The present invention has been described generally and/or specifically with respect to materials used in testing and testing methods. Although many materials and methods of operation are known in the art for the purpose of carrying out the invention, the invention is nevertheless described herein in as detail as possible. The following examples further illustrate the invention without limiting it.

Preparation of natural ancrod: the present inventors have referred to the William Burkhart reference plan for obtaining natural ancrod glycoprotein shown in Lane 3 of FIG. 1A, and have used natural glycosylated protein, i.e., natural ancrod, in the present invention as a control, using Agkistrodon malabaricus venom as a starting material.

Example 1: construction of Gene expression vector encoding recombinant protein of ancrod

The present invention obtains gene expression vectors commercially (AutekBio), and although the construction methods of such gene expression vectors are well known and commonly used in the art, the present invention is described in detail below, but the detailed description is not intended to limit the present invention.

(1) Host cell

Adopting CHO cell (ATK-CHO-SX) cultured in serum-free suspension as host cell, and culturingThe conditions were 37 ℃ and 5% CO₂120rpm, cell doubling time (PDT) of about 17 hours per 2-3 days of subculture, maximum viable cell density of up to 1 × 10 in batch culture⁷Individual cells/mL.

(2) Genetically engineered plasmids

The ATK-V03-aSP vector is a vector autonomously constructed by AutekBio for secretory expression of recombinant proteins in mammalian cells. The ATK-V03-aSP vector contains a CMV promoter, a BGH pA tailing signal and a Neo screening marker gene for screening a stable expression cell in a eukaryotic cell. The ATK-V03-aSP vector also contains a replication initiation site derived from the plasmid pMB1 and an ampicillin resistance gene, and can be screened and replicated in Escherichia coli. The source and function of the main components of the ATK-V03-aSP vector and the nucleotide sequence of each control region on both sides of the insertion site of the target gene are shown in tables 1 to 3.

Table 1: ATK-V03-aSP vector main component element

Component element	Origin of origin	Function(s)
			pUC replication initiation site	pMB1	The starting plasmid replicates in prokaryotic systems
CMV promoters	Human cytomegalovirus	Initiation of transcription of a Gene of interest
			polyA signal	Artificial operationSynthesis of	Stabilization of mRNA
Neo gene coding region	Artificially synthesized	Eukaryotic screening
			Ampicillin resistance coding region	pBR322	Prokaryotic screening

Table 2: nucleotide sequence of control region at two sides of target gene insertion site of ATK-V03-aSP vector

Table 3: analysis of enzyme cutting site of ATK-V03-aSP vector

#	Name	Recognition Site	No	Position(s)
					1	AgeI	A^CCGGT	1	1192.
2	ApaLI	G^TGCAC	3	170,4241,5487.
					3	AvaI	C^YCGRG	2	1308,2416.
4	BamHI	G^GATCC	1	1321.
					5	BglII	A^GATCT	1	150.
6	EcoRI	G^AATTC	1	1258.
					7	EcoRV	GAT^ATC	2	1275,2430.
8	HindIII	A^AGCTT	1	1183.
					9	KpnI	GGTAC^C	1	1193.
10	MluI	A^CGCGT	1	1198.
					11	MunI	C^AATTG	1	299.
12	NcoI	C^CATGG	4	867,1208,2302,3037.
					13	NdeI	CA^TATG	1	741.
14	NheI	G^CTAGC	1	1294.
					15	NotI	GC^GGCCGC	1	1314.
16	NsiI	ATGCA^T	2	2145,2217.
					17	PstI	CTGCA^G	1	2658.
18	PvuI	CGAT^CG	1	5190.
					19	SacI	GAGCT^C	1	1075.
20	SacII	CCGC^GG	2	1162,1320.
					21	SalI	G^TCGAC	2	136,3553.
22	SmaI	CCC^GGG	1	2418.
					23	StuI	AGG^CCT	1	2394.
24	XhoI	C^TCGAG	1	1308.
					25	XmaI	C^CCGGG	1	2416.

The coding DNA sequence of the Ancrod glycoprotein is completed by a chemical synthesis method, the synthesized DNA coding sequence is connected into an ATK-V03-aSP vector by using T4DNA ligase to obtain a gene recombination expression plasmid ATK-V03-aSP-Ancrod, and the correctness of an insertion sequence in the recombination plasmid is verified by DNA sequencing. The plasmid map is shown in FIG. 1.

Example 2: stable expression of recombinant ancrod in mammalian host cells

Establishment, cloning and screening of ancrod glycoprotein high expression and high yield gene engineering cell strain

The V03-aSP-Antcrod and V07-DHFR-neo plasmids are co-transformed into the host cell ATK-CHO-S2 by a shock transfection method. After transfection, cells were placed at 37 ℃ in 5% CO₂Culturing in an incubator. After 24 hours of culture, the cells were inoculated into a screening medium (formulation: tryptone 5.0g/L, polypeptone 5.0g/L, beef powder 3.0g/L, glucose 1.0g/L, sodium chloride 5.0g/L, disodium hydrogen phosphate 1.0g/L, glycine 10.0g/L, lithium chloride 0.5g/L, phenethyl alcohol 2.5g/L, agar 15.0g/L, pH 7.3) for screening. 27 cell lines expressing ancrod glycoprotein are obtained in total.

According to the result of batch culture, five monoclonal cell strains CIAS1, CIA-P4, CIA-P8, CIA-P33 and CIA-P48 with high ancrod glycoprotein expression are selected for continuous screening, and are inoculated into a 96-well plate according to the inoculation density of less than 5 cells per well for subclone screening. The obtained subclones were cultured in 24-well plates for 4-6 days, and then activity was measured. According to the activity determination result, selecting the clone with higher expression activity, transferring the clone into a 6-hole plate, continuously culturing for 3 days, and then performing activity determination. According to the activity determination result, the clone with higher expression activity is selected and transferred into a 50mL shake flask for culture. And selecting CIA8-64 clones according to the batch culture result. And further carrying out subclone screening on the CIA8-64 clone to finally obtain a stable and high-expression monoclonal cell strain CIA 8-64-33-95. The activity detection is carried out by adopting a blood coagulation instrument, and the activity is considered according to the blood coagulation speed.

Example 3: cellular production of recombinant ancrod proteins

This example describes the cell culture and scale-up process.

(1) A small trial process: CIA8-64-33-95 was cultured in a 10 liter bioreactor of Saedodes (Sartorius) BIOSTAT B PLUS under the following process conditions:

initial culture volume: 5 liters of water

Basic culture medium: SFM

The culture conditions are as follows: 37 ℃ and 5% CO₂、120rpm

Inoculation density of 0.3 × 10⁶One/ml.

The composition of serum-free medium (SFM) was: glucose 0.6%, glutamine 2mM, NaHCO 33 mM, Hepes 5mM, insulin 2.5. mu.g/ml, transferrin 100ng/ml, butanediamine 60. mu.M, sodium selenate 30nM, penicillin 50. mu.g/ml, streptomycin 50. mu.g/ml, cupric chloride 100. mu. M, N-acetyl-D-aminommannose 2mM, potassium pyrophosphate 50. mu. M, DF12 to 100 ml.

Bioreactor parameters were set as follows:

DO (air saturation): 50 percent of

The pH range is as follows: 6.8 to 7.2

Stirring speed: 120 revolutions per minute

And (3) ventilation mode: surface aeration (air) and deep aeration (air, oxygen and carbon dioxide).

(2) Pilot plant test process

The culture process of the CIA8-64-33-95 cell strain in a 50-liter bioreactor is as follows:

initial culture volume: 50 liters of the product

Basic culture medium: as above

The culture conditions are as follows: 37 ℃ and 5% CO₂、120rpm

Inoculation density of 0.3 × 10⁶One/ml.

Setting parameters of the bioreactor:

DO (air saturation): 50 percent of

The pH range is as follows: 6.8 to 7.2

Stirring speed: 120 revolutions per minute

In the above (1) pilot test process and (2) pilot test process, the serum-free culture medium is added with copper chloride, N-acetyl-D-amino mannose and potassium pyrophosphate, and the culture can reach 1.0-1.2 × 10 after the culture is carried out at 37 ℃ for 6-7 days⁷Reducing the temperature from 37 ℃ to 33 ℃, continuing culturing (about 3-4 days) until the cell density is not increased any more, and harvesting the culture, wherein the cell density can reach 2.8-3.0 × 10 at the maximum⁷Level of individual cells/mL.

Supplementary test referring to the "(1) pilot test process" and "(2) pilot test process" of example 3, except that after the highest viable cell density was reached by the culture to day 7, the bioreactor was continued to be cultured at 37 ℃ without adjustment for 12 days, and the cell density was found to reach about 1.0 to 1.2 × 10 by the culture to days 6 to 7⁷The density cannot be increased any more after the level of individual cells/mL, and the cell density tends to decrease even at days 8-9. In this experiment in which the culture temperature was not changed (decreased), the cell growth and the expression of the target protein in the pilot process are shown in FIGS. 2 and 3, and the cell growth and the expression of the target protein in the pilot process are shown in FIGS. 4 and 5.

(3) Quantitative analysis method of ancrod glycoprotein

Since ancrod glycoprotein causes plasma agglutination, a quantitative analysis method of ancrod glycoprotein employs a plasma agglutination method.

The instrument comprises the following steps: a policosan C2000-1 hemagglutination instrument, a disposable measuring cup and a special steel ball for the hemagglutination instrument.

The method comprises the following steps: the frozen human plasma is placed in a constant-temperature water bath with the temperature of 37 +/-0.5 ℃ for thawing and is gently shaken up. The coagulometer and cuvette were preheated to 37. + -. 0.5 ℃. 200 μ l of plasma and steel beads were added to the cuvette. Add 100. mu.l of the sample to be tested to the cuvette and start the timer. The time for stopping the steel ball from swinging is the agglutination time. The sample to be detected is diluted in a proper amount according to the content concentration of the ancrod glycoprotein.

The quantitative analysis method can monitor the yield and the yield of the recombinant ancrod enzyme, the coagulation activity of materials and the like in the process. For example, in the above examples, it has been found that the method of the present invention can easily obtain a high expression level of recombinant ancrod enzyme in an industrial production specification, a yield of 200IU/ml or more per ml of fermentation broth, and a specific activity of 1000IU/mg or more.

Example 4: purification of recombinant ancrod

(1) Concentration of recombinant ancrod enzyme fermentation broth

Filtering the culture solution containing the recombinant ancrod enzyme obtained in the previous step to remove cell debris, and collecting filtrate; 50L fermentation liquor is harvested every time, the sample needing to be purified is large in size, and a large amount of small molecular substances exist in the sample, so that the purification is not facilitated. Ultrafiltering the fermentation broth with ultrafiltration membrane with cut-off molecular weight of 30K, concentrating to obtain supernatant with blood coagulation activity of 10-20S, and discarding the supernatant with blood coagulation activity of more than 200S. And (4) carrying out next ultrafiltration membrane purification on the membrane supernatant until the volume is reduced to 1/8-1/10 of the original volume.

The process flow of fermentation liquor concentration is exemplified as follows: 50L of fermentation liquor (with blood coagulation activity of 10-20S) -30K ultrafiltration membrane-10L of membrane supernatant is discarded, and the blood coagulation activity of membrane supernatant is greater than 200S-membrane supernatant for further purification.

(2) Affinity column chromatography on Heparin Sepharose6Fast Flow gel

A chromatographic column (column diameter is 50mm, length is 12cm), a packing is a Heparin Sepharose6Fast Flow, an equilibrium buffer is 0.05mol/L Tris-HCl pH7.0-7.5 buffer, a sample is 1000mL of the membrane supernatant in the step (1), the sample is diluted to 2000mL by the equilibrium buffer, and the column Flow rate is 24 mL/min. After loading, the sample is equilibrated to baseline with equilibration buffer, eluted with 0.25mol/L NaCl, 0.05mol/L Tris-HCl pH7.0-7.5 buffer, and the active fraction is collected. Eluting with 1.0mol/L NaCl and 0.05mol/L Tris-HCl pH7.0-7.5 buffer solution to remove impurity components, washing the chromatographic column with 1000ml of equilibration buffer solution, and regenerating for use. The chromatogram of the affinity column chromatography on Heparin Sepharose6Fast Flow column in the first step of purification is shown in FIG. 6.

(3) Purification by reverse phase liquid chromatography

Purifying the obtained recombinant ancrod protein by a preparative reverse phase liquid chromatography technology, and further removing other impurities by using a gradient elution method of an ethanol-water system by utilizing the difference of polarity. Sample application

Separating by preparative high performance liquid chromatographFrom the preparation, the column was a Dubbe C4 column (10 μm, Φ 20 × 250mm,

). Washing ethanol in a flow path of the system with 500mL of pure water and balancing the chromatographic column at a flow rate of 10mL/min, then loading the active component collected in the step (2) by a liquid chromatography infusion pump at a flow rate of 10mL/min, and after loading, washing the pipeline and the chromatographic column with 100mL of pure water.

Gradient elution was performed according to Table 4, wherein mobile phase A was an aqueous solution of phosphoric acid (pH2.3), mobile phase B was ethanol, and 1% propylene glycol was additionally added to each of mobile phase A, B, the detection wavelength was 214nm, and the elution flow rate was 20 mL/min.

Table 4: elution conditions Table

Time/min	A	B
				0～50	90→30	10→70
50～60	30	70
			61.～71	90	10

The main peak of activity was collected and diluted 10-fold with water. And (5) carrying out the next purification.

Purification treatment the second reversed phase liquid chromatography purification chromatogram is shown in FIG. 7. As shown in FIG. 7, the target glycoprotein can be eluted within the range of 2000 to 2200 ml. In supplementary experiments, the inventor finds that if propylene glycol is not added into the mobile phase A, B, the target glycoprotein is eluted by the required volume in the range of 2500-2900, the elution time is prolonged, the volume of the used mobile phase is larger, and the protein concentration of the obtained eluent is lower.

(4) Affinity column chromatography on Heparin Sepharose6Fast Flow gel

A chromatographic column (the diameter of the column is 50mm, the length is 12cm), a packing is a Heparin Sepharose6Fast Flow, an equilibrium buffer is 0.05mol/L Tris-HCl pH7.0-7.5 buffer, a sample is an activity main peak in the step (3), the activity main peak is diluted to 1000mL by the equilibrium buffer, and the sample is loaded, and the Flow rate of the column is 2 mL/min. After loading, the sample was equilibrated to baseline with equilibration buffer, eluted with 0.25mol/L NaCl, 0.05mol/L Tris-HCl pH7.0-7.5 buffer, and the active fractions were collected. Eluting with 1.0mol/L NaCl and 0.05mol/L Tris-HCl pH7.0-7.5 buffer solution to remove impurity components, washing the chromatographic column with 1000ml of balance buffer solution, and regenerating for use.

The purification method of this example 4 can effectively separate recombinant proteins, and the purity of glycoproteins is greater than 99% by reverse phase chromatography.

Example 5: structural analysis of recombinant ancrod

(1) N-terminal and C-terminal determination of 15 amino acid residues:

the protein sequence was identified by LTQ-MS, and the recombinant ancrod enzyme obtained in example 4 was subjected to sequence determination of 1-15 amino acid residues at the N-terminus, and the sequence was: VIGGDECNINEHRFL are identical to known sequences; the C-terminal 217-234 amino acid sequence DYRDWVNNVIAGNATCSP is identical to the known sequence. The complete amino acid sequence determination shows that the recombinant ancrod enzyme sequence is identical to the amino acid sequence of ancrod enzyme carried by http:// www.uniprot.org.

(2) Disulfide bond:

the primary structure of the recombinant ancrod enzyme is determined to be a single chain containing 234 amino acid residues, has 6 pairs of disulfide bonds, is respectively positioned at C7-141, C28-44, C78-232, C120-C188, C152-167 and C178-203, and is consistent with the known sequence.

(3) Glycosylation structure:

obtaining glycosylation modified peptide fragments by protease enzymolysis of protein, high-precision LC-MS mass spectrum detection and mass spectrum data analysis software Pepfinder TM to perform qualitative and quantitative analysis of glycopeptide level.

The result shows that the recombinant ancrod enzyme contains 5N-Link glycosylation sites which are respectively positioned in: asn (n)²³-Trp²⁴-Thr²⁵，Asn⁷⁹-Lys⁸⁰-Thr⁸¹，Asn⁹⁹-Asn¹⁰⁰-Ser¹⁰¹，Asn¹⁴⁸-Phe¹⁴⁹-Thr¹⁵⁰And Asn²²⁹-Ala²³⁰-Thr²³¹The glycosylation sites of the known ancrod enzymes are the same as those carried by http:// www.uniprot.org.

The isoelectric points of the recombinant ancrod prepared in each experiment of the invention are all in the range of 4.5-5.5 by determination.

Determination of the molecular weight of the glycoprotein: the molecular weight of the recombinant ancrod glycoprotein prepared by the method and the natural ancrod glycoprotein is determined by adopting a liquid chromatography-mass spectrometry method, and the result shows that the average molecular weight of the recombinant ancrod glycoprotein of each batch obtained by the method is within the range of 39-41 kDa, and the molecular weight distribution range is within the range of 33-52 kDa (the distribution span is over 17 kDa); for example, the average molecular weight of the recombinant ancrod glycoprotein sample of the 20140509 batch of the invention is 40544Da, the molecular weight distribution range is 33980-51841 Da (the distribution span reaches 17.9kDa), and the LC-MS diagram of the sample is shown in FIG. 8; the average molecular weight of the natural ancrod glycoprotein is 37.7kDa, the molecular weight distribution range is 32.1-40.8 kDa (the distribution span is 8.7kDa), and the distribution span is far smaller than that of the recombinant glycoprotein (an LC-MS diagram of the natural ancrod glycoprotein is not shown).

Supplementary test of the influence of process conditions on the degree of glycosylation: referring to the methods of examples 1-4 above, except that in the pilot and pilot processes of example 3, the composition of the serum-free medium is changed, i.e., the average molecular weight of the glycoproteins obtained under the conditions (either small or pilot) is determined to be in the range of 38.3-39.1 kDa and 34-45 kDa (the distribution span is no more than 11kDa), which indicates that the glycosylation level of the glycoproteins is low. In addition, the specific activities of the less glycosylated glycoproteins obtained in the present supplementary test were measured according to the method for measuring the specific activities described in example 6, and all of the results were in the range of low specific activities of 883 to 976 IU/mg. In addition, the stability of the less glycosylated glycoprotein obtained in this supplementary test was measured according to the stability test method described in example 6, and the relative activity was found to be in the range of 74 to 88%. This supplementary experiment suggests that the use of a serum-free medium containing copper chloride, N-acetyl-D-aminommannose and potassium pyrophosphate is useful for obtaining a glycoprotein having more excellent performance when cell culture is performed.

Example 6: in vitro activity assay of recombinant ancrod enzyme

Sample preparation: example 4 batches of recombinant ancrod enzyme, various supplementary tests of recombinant ancrod enzyme, natural ancrod enzyme, etc.

The activity determination method comprises the following steps:

the principle is as follows: since the recombinant ancrod can degrade fibrinogen in blood into fibrin and coagulate the blood, the activity of the recombinant ancrod can be determined by measuring the coagulation time of plasma or fibrinogen.

Instruments and materials:

the hemagglutination instrument, the trihydroxymethyl aminomethane, the sodium hydroxide, the calcium chloride and the concentrated hydrochloric acid are domestic analytical pure reagents; the water is double distilled water. Bovine fibrinogen (bovine blood) (88mg soluble protein/stick), batch number: 140607-201137; bovine blood albumin is an imported subpackaged reagent.

Preparation of test solution

2mol/L Tris-hydrochloric acid diluent stock solution: dissolving 12.1g of tris (hydroxymethyl) aminomethane in 80ml of water, adjusting the pH value to 7.4 with 1mol/L hydrochloric acid solution, adding water to 100ml, and shaking up to obtain the final product.

20mmol/L Tris-hydrochloric acid diluent: taking 0.5mL of the stock solution, adding water to a constant volume of 50mL, and mixing uniformly to obtain the finished product.

Phosphate diluent (ph 6.0): dissolving 0.17g of disodium hydrogen phosphate and 0.85g of sodium chloride in 80mL of water, adjusting the pH value to 6.0 by 1mol/L of sodium hydroxide, adding water to 100mL, and shaking up to obtain the sodium hydrogen phosphate.

0.5% bovine blood albumin-20 mNTris-hydrochloric acid diluent: taking 0.05g of bovine serum albumin, adding 20 mNtiris-hydrochloric acid diluent for dissolving, fixing the volume to 10mL, and shaking up to obtain the bovine serum albumin.

0.5% bovine serum albumin-phosphate diluent (ph 6.0): taking 0.05g of bovine serum albumin, adding 20 mNtiris-phosphate diluent for dissolving, fixing the volume to 10mL, and shaking up to obtain the bovine serum albumin.

Bovine fibrinogen working solution: taking 1 bovine fibrinogen standard reagent of China food and drug testing research institute, adding 11mL of diluent to prepare stock solution with the concentration of 8mg/mL, and then diluting the stock solution with the diluent to working solution with the concentration of 4 mg/mL.

The determination method comprises the following steps:

preparation of control solutions: taking 1 recombinant ancrod enzyme working reference substance, adding a proper amount of diluent to prepare a reference substance mother solution of 10IU/mL, then respectively taking 800 muL, 600 muL, 400 muL and 200 muL standard solutions, adding the diluent to a constant volume of 1mL, accurately diluting to a solution with the concentration of 6.0, 4.0, 2.0 and 1.0IU/mL, placing in a heat preservation hole of a hemagglutination instrument when in use, and preserving heat at 37 ℃.

Preparation of a test solution: precisely measuring an appropriate amount of the product, and adding a diluent to prepare a solution containing about 2-6 IU per 1 ml.

Preparation of a standard curve: taking 0.2mL of bovine fibrinogen working solution, respectively placing the bovine fibrinogen working solution in 3 measuring cups in sample measuring holes of a hemagglutination instrument, preserving the heat at 37 ℃ for 3 minutes, respectively precisely measuring 0.1mL of preheated reference substance solution, quickly adding the bovine fibrinogen working solution into each cup of the fibrinogen solution, and automatically recording the solidification time by the instrument. Each concentration was measured in 3 replicates and the mean and standard deviation were calculated (again when the standard deviation was greater than 3.0 seconds). The regression equation was calculated as the logarithm of the concentration of the control solution and the logarithm of the mean value of its clotting time.

The determination method comprises the following steps: precisely measuring 0.1ml of the product, placing the product in a coagulometer for preheating in a water bath at 37 ℃, measuring the coagulation time according to the method under the preparation item of a standard curve, calculating the average value and the standard deviation (the standard deviation meets the preparation requirement of the standard curve) of the 3 times of measurement results, and calculating the titer of the recombinant ancrod enzyme by a regression equation to obtain the recombinant ancrod enzyme.

And (3) sample determination: four batches of heavy ancrod enzyme stock solutions obtained by the method of the invention in the embodiment 4 are taken, and the results of the measurement according to the method are shown in the table 5, and the potency is more than 270 IU/mL.

Table 5: result of potency assay of recombinant ancrod enzyme stock solution

Batch number	potency/(IU/mL)
		20140509	362.11
20140521	271.29
		20140610	503.15
20140524	649.40

Measurement of specific Activity: the protein content and the activity of the recombinant ancrod prepared from different batches in the embodiment of the invention are measured, the specific activity of glycoprotein is represented by IU/mg, and the result shows that the specific activity of the recombinant ancrod glycoprotein prepared by the invention reaches the range of high specific activity of 1135-1462 IU/mg; unfortunately, the specific activity of the native ancrod glycoprotein was similarly determined to be only 865 IU/mg. This difference in specific activity is probably due to the difference in the amino acid exo-chain modified sugars, and suggests that the more complex and intact the modified sugars are, the higher the activity of the glycoprotein.

And (3) stability investigation: in the embodiment of the invention, the recombinant ancrod enzymes (four batches in table 5) and the natural ancrod enzymes prepared in different batches are dissolved in a buffer solution with the pH value of 6.5, a protective agent is not added, and the buffer solution is placed under a refrigeration condition of 2-6 ℃ for 6 months, and the result shows that the in vitro activity of the recombinant ancrod enzymes under the stability investigation condition is not reduced basically, and the relative activity of the recombinant ancrod enzymes is 93-96% in 6 months compared with 0 month; surprisingly, the relative activity of native ancrod was only 61.5%, much lower than that of recombinant glycoproteins. The term "relative activity" refers to the percent of activity of a sample measured at 6 months divided by the activity measured at 0 months multiplied by 100%. This difference in stability may be due to the difference in modified sugars of the recombinant and native ancrod enzymes coat, and suggests that the more complex and intact the modified sugars are, the higher the stability of the glycoprotein.

Example 7: dissolution of dog middle cerebral artery thrombotic blood clot and cerebral ischemia injury by recombinant ancrod enzyme Influence of

The purpose is as follows: the protective effect of the recombinant ancrod enzyme on the dissolution of arterial thrombus and cerebral ischemic injury in dogs and the blood coagulation and fibrinolysis effect after dog thrombus are observed.

The method comprises the following steps: a model of persistent cerebral ischemia caused by the injection of thrombotic blood clots into the middle cerebral artery of a dog. The test was divided into 5 groups, model control group, recombinant ancrod high dose group (0.68IU/kg), medium dose group (0.34IU/kg), low dose group (0.17IU/kg) and batroxobin group (0.34 BU/kg). The tested medicine is absorbed according to the weight of the body and injected into 100ml of physiological saline, intravenous infusion administration is carried out 10min after the operation, and the administration time is controlled to be 35-45 min. The control group was intravenously infused with an equal amount of physiological saline.

As a result: the recombinant ancrod enzyme has good dissolving effect on the thrombotic blood clots of middle cerebral artery of dog in high, middle and low doses, and the cerebral infarction areas are respectively reduced by 89.9%, 82.5% and 59.2% compared with the control group of the model group. The recombinant ancrod enzyme small-dose group and the batroxobin group have similar effects on reducing the cerebral infarction area. The blood flow recovery rate of the right internal carotid artery 24 hours after the drug administration is 42.7 percent, 36.2 percent and 23.6 percent respectively.

The recombinant ancrod has the advantages of obviously reducing the functional behavior symptoms of neuromuscular, reducing the score of neurobehavioral indexes and having obvious protective effect on ischemic injury of local brain caused by arterial thrombotic blood clots in the middle cerebral artery of an infarcted dog.

After the intravenous drip of the recombinant ancrod enzyme with high, medium and low doses for 6 hours, the plasma Prothrombin Time (PT), the Thrombin Time (TT) and the Activated Partial Thrombin Time (APTT) of the middle cerebral artery thrombosis dog are obviously prolonged. The incidence of FIB elongation of canine plasma of 100%, 83.3%, 100%, 66.7% in the high, medium and low dose groups and batroxobin groups of recombinant ancrod for more than 60s and FIB content less than 0.5 g/L. The canine plasma Thrombin Time (TT) is significantly prolonged 24h after high dose group medication, the incidence of canine plasma FIB prolongation of more than 60s and FIB content of less than 0.5g/L is 83.3%.

After intravenous infusion of the recombinant ancrod enzyme with high, medium and low doses, a great amount of blood exudation occurs to the surgical wounds of dogs, the incidence rate of the blood exudation of the wounds is 100%, 66.7% and 50% 6h after administration, and the incidence rate of the blood exudation of the wounds is 66.7%, 16.7% and 0 h 24h after administration. The estimated value of the wound bleeding amount is between 20ml and 100ml, the wound bleeding amount is related to the administration dosage, the wound bleeding amount of the high-dosage group is large, and the duration is long. The incidence of blood exudation in the batroxobin group was 50% at 6h after administration.

Example 8: single-dose toxicity test of SD rat by intravenous injection administration of recombinant ancrod

In the experiment, the recombinant ancrod enzyme is administered by single intravenous injection of SD rats, and the acute toxic reaction condition caused by the recombinant ancrod enzyme is observed.

In the experiment, 3 groups of 10 animals each with half of male and female are respectively administered with a solvent control (0 mug/kg, 0.9% sodium chloride injection), 160 and 320 mug/kg of recombinant ancrod by single intravenous injection, the administration volume is 5mL/kg, and the observation period is 14 days. The following indicators were observed or tested during the test: death and moribund status of animals, clinical signs, body weight. At the end of the observation period, the animals were examined for gross dissection. Since no gross anatomy was abnormal, no histopathological examination was performed.

In the 320. mu.g/kg group and the 160. mu.g/kg group, 1 animal died on the day of administration, and decreased activity, inability to stand, and double hind limb paralysis were observed before the death, which was associated with the test article.

The 320 and 160 μ g/kg groups exhibited reduced activity, inability to stand, paralysis or stiffness of both hind limbs, tachypnea, disappearance of righting reflex, and a dose-related response in animals from about 1 minute after administration to 5 minutes after administration. Urine was observed to be deep red in both the 320 and 160 μ g/kg groups of surviving females at approximately 10 and 30 minutes post-dosing. In addition, a reduction in activity was observed 30 minutes after administration in 3 males surviving the 320 μ g/kg group, with hair piloerection in 2 males continuing until 2 hours after administration. Only 1 male seen reduced activity 30 minutes after the 160. mu.g/kg group was administered. No abnormality was observed in the cases of the animals surviving in the 320 and 160. mu.g/kg groups from 4 and 2 hours after the administration to the end of the observation period. No abnormality is found in the male and female animals at 0 mug/kg during the test period.

During the test period, no abnormality related to the test article is found in the body weight and pathological examination of the animals in the test article group.

In summary, under the conditions of this experiment, SD rats were administered 160 and 320. mu.g/kg recombinant ancrod by single intravenous injection. The recombinant ancrod enzyme with the dosage of more than or equal to 160 mu g/kg can cause the reduction of activity, incapability of standing, paralysis or stiffness of double hind limbs, tachypnea, disappearance of righting reflex and deep red urine of animals, can also cause the pilosis of the animals under the dosage of 320 mu g/kg, and can be recovered within 2-4 hours after the change of administration. Thus, under the conditions of this experiment, the Maximum Tolerated Dose (MTD) of recombinant ancrod in SD rats given by a single intravenous injection was less than 160. mu.g/kg.

Example 9: SD rat intravenous injection recombinant ancrod enzyme four-week recovery period four-week repeated administration toxicity test

The purpose of the test is to administer the recombinant ancrod enzyme by continuous intravenous injection for four weeks to SD rats, administer the recombinant ancrod enzyme for 1 time every other day, observe the toxic reaction caused by the recombinant ancrod enzyme and study the pharmacokinetic characteristics of the recombinant ancrod enzyme in the recovery period for four weeks, provide target organs of the toxic reaction of the recombinant ancrod enzyme, observe the reversible condition of damage after the recovery period for four weeks, and provide reference for clinical tests.

144 SD rats are used in the test, each group comprises 30 rats, and the rats are half male and female; TK groups, 6 TK groups, and male and female halves. The recombinant ancrod was administered intravenously at doses of 20, 40, 80 μ g/kg. The preparation is administered 1 time every other day, with a dose volume of 5mL/kg, a dose period of 29 days (D1-D29), and a recovery period of 28 days (R1-R28).

The following observations or measurements were made during the experiment: observation of death and moribund conditions, observation of clinical signs, weighing of body weight, food intake testing, ophthalmic testing, pharmacokinetic analysis, urinalysis, hematological and coagulation indicators, serum biochemical indicators, gross anatomy, organ weight, and histopathological examination.

The pharmacokinetic results show that: the exposure amount of the recombinant ancrod enzyme in the plasma of female rats and male rats under the same dose after the first administration is not different, the exposure amounts are linearly related, and the exposure amount of the recombinant ancrod enzyme is not accumulated after 29 days of continuous administration.

The test results show that: during the experiment, 1 death was observed in the 80 μ g/kg dose group about 5 minutes after D3 administration, and reduced activity, inability to stand and urine discoloration (deep red) were observed before death, and no abnormality related to the test article was observed in gross dissection and histopathological examination.

Urine discoloration (light red) was observed in 40 μ g/kg group females on the day of administration during the first week of administration. The urine discoloration (deep red) is seen on the administration day of 80 mug/kg group male and female animals in the administration period, the activity is reduced about 2-5 minutes after the administration, and in addition, the sexual incapability of standing, soft stool and perianal pollution are caused on the administration day of male animals in the administration period. No obvious abnormality is observed in clinical observation of the animals in the non-administration days and the recovery period of the administration period.

The food intake of the male animals in the 80 mug/kg group is reduced in the first week of the administration period, and the body weight is not abnormal.

At the end of the dosing period, the average RBC in females was significantly decreased and the average% RETIC in males and females was significantly increased in the 80 μ g/kg group compared to the 0mg/kg group. The abnormality above the recovery period is recovered.

At the end of the administration period, 80. mu.g/kg of urine of the male and female animals showed brown to dark red, hematuria and urine protein, while the urine of the male animals was turbid. Recovery is seen at the end of the recovery period.

Histopathological examination revealed that at the end of the dosing period, the spleen was extramedullary hematopoietic in 80. mu.g/kg groups of male animals. Recovery was seen at the end of the recovery period.

During the experiment, no obvious abnormality is found in the body weight, ophthalmic examination and serum biochemistry of all the animals in the dose groups.

In summary, in this experimental condition, SD rats were given recombinant ancrod intravenously at doses of 0 (0.9% sodium chloride injection), 20, 40, 80 μ g/kg every two days for four weeks following a recovery period. At a dose of 40 μ g/kg, the female was seen to develop a transient urine discoloration (light red); at 80 μ g/kg, urine discoloration is aggravated (deep red), motility is reduced,% RETIC is increased, hematuria and urine protein are reduced, RBC is reduced in female animals, transient non-standing and food intake is reduced in male animals, stool is softened, perianal pollution is reduced, and spleen extramedullary hematopoiesis is observed in histopathological examination. All abnormalities above the recovery period are recovered. No sex difference was observed in the exposure amount of the plasma recombinant ancrod enzyme in each dose group, and the exposure amount was linearly related, and no accumulation was observed after 29 consecutive days of administration. No toxic effect was observed in males and females (NOAEL, No observedadversie effect level) at 20 and 40. mu.g/kg, respectively.

Example 10: injection composition of recombinant ancrod enzyme

The recombinant ancrod enzyme is expected to be directly injected in the form of injection clinically, and the preparation form is favorable for acute treatment of acute cerebral infarction. However, the recombinant ancrod product prepared above contains Tris, and is not suitable for direct injection in human, so that it is urgently needed to prepare a composition, especially a liquid composition, suitable for direct injection in human.

1. Preparation of stock solution

According to the invention "example 4: method for producing recombinant ancrodPurification ", but the procedure"(4) The equilibration buffer and elution buffer in the Heparin Sepharose6Fast Flow gel affinity column chromatography "were changed to PBS-LYS buffer, which contained: 0.2 percent of sodium chloride, 0.1 percent of L-lysine hydrochloride, 15mmol/L sodium dihydrogen phosphate, sodium hydroxide for adjusting the pH value to 6.8, and proper amount of water to the full amount.

The specific procedure "(4) Heparin Sepharose6Fast Flow gel affinity column chromatography" was as follows: chromatography column (column diameter 50mm, length 12cm), packed with Heparin Sepharose6Fast Flow, PBS-LYS buffer containing: 0.2% sodium chloride, 0.1% L-lysine hydrochloride, 15mmol/L sodium dihydrogen phosphate and sodium hydroxide to adjust pH to 6.8, and water to full volume, wherein the sample is the main active peak in step (3), and is diluted to 1000mL with PBS-LYS buffer solution, and the column flow rate is 2 mL/min. After loading, the sample was equilibrated to baseline with PBS-LYS buffer, eluted with PBS-LYS buffer, and the active fractions were collected. Eluting with PBS-LYS buffer solution to remove impurity components, washing the column with PBS-LYS buffer solution 1000ml, and regenerating. Thus, a stock solution of recombinant ancrod of this example 10 was obtained, which contained only 0.25% sodium chloride, 0.1% lysine hydrochloride, 15mM sodium dihydrogen phosphate, and recombinant ancrod protein.

2. Detection of recombinant ancrod enzyme of example 10

The purification method of this example 10 can effectively separate out recombinant protein, and the purity of the obtained recombinant ancrod glycoprotein is 99.8% by reverse phase chromatography analysis.

Referring to "example 5: the results of the structural analysis "of recombinant ancrod enzyme show that the results of the recombinant protein obtained in this example 10 are completely consistent with those shown in the examples, for example, the isoelectric point is 4.83. The average molecular weight of the recombinant ancrod glycoprotein sample is 40650Da, the molecular weight distribution range is 34200-51750 Da (the distribution span reaches 17.55kDa), and the LC-MS diagram of the sample is basically the same as that of FIG. 8.

Referring to "example 6: recombinant ancrod enzyme in vitro activity assay ", the results show that the recombinant protein obtained in example 10: the titer is 635IU/mL, the specific activity is 1532IU/mg, the relative activity of the stock solution for 6 months after being placed under the refrigeration condition of 2-6 ℃ for 6 months relative to 0 month is 99.8%, the relative activity of the stock solution for 6 months after being diluted to 20IU/mL by PBS containing lysine and the like and being placed under the refrigeration condition of 2-6 ℃ for 6 months is 99.4%, and the result shows that the stock solution and the diluent in the embodiment have excellent stability.

Referring to "example 7: test on the effects of recombinant ancrod on the dissolution of canine middle cerebral artery thrombotic blood clots and cerebral ischemic injury "the results of the test on the recombinant ancrod obtained in example 10 show that the high, medium and low doses of the recombinant ancrod in example 10 have good dissolution effects on canine middle cerebral artery thrombotic blood clots, the cerebral infarction areas are respectively reduced by 94.3%, 88.5% and 67.3% compared with the control group of the model group, and the right internal carotid blood flow recovery rates after 24 hours after the administration are respectively 56.6%, 43.7% and 29.3%. Intravenous infusion example 10 after high, medium and low doses of recombinant ancrod enzyme, there was a great deal of blood exudation in canine surgical wounds, and the incidence of blood exudation in wounds 6h after administration was 96.3%, 61.4%, 46%. 3 percent, and the incidence rate of wound blood exudation 24 hours after administration is 43.2 percent, 8.3 percent and 0.

Referring to "example 8: SD rat intravenous injection recombinant ancrod enzyme Single dose toxicity test "test the recombinant ancrod enzyme obtained in this example 10, and each result is substantially the same as that of example 8.

With reference to "example 9: SD rats were subjected to intravenous administration of recombinant ancrod for four-week recovery period and repeated administration toxicity test "the recombinant ancrod obtained in this example 10 was tested, and the results were substantially the same as those in example 9.

3. Preparation of injection

(1) The recombinant ancrod enzyme stock solution prepared in the embodiment 10 is diluted to the titer of 20IU/mL by PBS-LYS buffer solution, filtered and sterilized by a 0.22um microporous filter membrane, and is subpackaged into ampoules with 1mL per bottle, and then is sealed by melting to obtain the injection 101.

(2) The recombinant ancrod solution prepared in example 4 was diluted to 20IU/mL with 1.0mol/L NaCl and 0.05mol/L Tris-HCl buffer pH7.0-7.5, sterilized by filtration through a 0.22um microfiltration membrane, dispensed into ampoules at 1mL per vial, and sealed by fusion to give injection 102.

(3) Referring to the method of example 10, but without lysine in PBS-LYS buffer, recombinant ancrod stock was prepared by diluting the stock to 20IU/mL titer with PBS buffer without lysine, filtering and sterilizing with 0.22um microporous membrane, packaging into ampoules at 1mL per vial, and sealing by fusion to obtain injection 103.

(4) Referring to the method of example 10 but without adding sodium chloride to PBS-LYS buffer, recombinant ancrod stock solution was prepared by diluting the stock solution to 20IU/mL with PBS-LYS buffer without adding sodium chloride, sterilizing by filtration through 0.22um microporous membrane, packaging into ampoules at a volume of 1mL per vial, and sealing by fusion to obtain injection 104.

(5) Referring to the method of example 10, but changing lysine to equal amount of L-arginine hydrochloride (same as lysine, basic amino acids) in PBS-LYS buffer solution, recombinant ancrod stock solution was prepared, and the stock solution was diluted to 20IU/mL with PBS-arginine buffer solution, sterilized by filtration with 0.22um microporous membrane, dispensed into ampoules with 1mL per vial, and sealed by fusion to obtain injection 105.

The injections 101 to 105 were allowed to stand at 2 to 6 ℃ for 18 months under refrigeration, the activity of each injection at 0 month and 18 months was measured, and the relative activity at 18 months to 0 month was calculated. As a result: 94.2% of injection 101, 76.3% of injection 102, 68.7% of injection 103, 74.4% of injection 104 and 77.5% of injection 105. It can be seen that the resulting injection exhibits excellent stability by performing final protein purification using PBS-LYS buffer and using the buffer as a carrier for injection formulation.

All the prepared injections 101 to 105 are colorless clear solutions; they were left at room temperature for months and observed for changes in the appearance of each injection, with the following results: the injection 101 remained colorless and clear, the injections 102 to 104 were opalescent and flocculated, and the injection 105 was white. Therefore, the injection 101 has significantly better physical stability and biological stability.

The spirit of the present invention is described in detail by the preferred embodiments of the present invention. It will be understood by those skilled in the art that any modification, equivalent change and modification made to the above embodiments in accordance with the technical spirit of the present invention fall within the scope of the present invention.

Claims

1. A method for purifying recombinant ancrod, which comprises purifying the recombinant ancrod protein by reverse phase liquid chromatography, and then performing Heparin Sepharose6Fast Flow gel affinity column chromatography purification by the following method:

a chromatographic column, wherein a filler is a Heparin Sepharose6Fast Flow, a sample is an active main peak of the recombinant ancrod protein purified by reverse phase liquid chromatography, the sample is diluted to 1000mL by PBS-LYS buffer solution and is loaded, and the Flow rate of the column is 2 mL/min; after loading, balancing to a baseline by using PBS-LYS buffer solution, eluting by using PBS-LYS buffer solution, and collecting active components; eluting impurity components with PBS-LYS buffer solution, washing the chromatographic column with PBS-LYS buffer solution for 1000ml, and regenerating to obtain recombinant ancrod enzyme stock solution;

the PBS-LYS buffer comprises: 0.2 percent of sodium chloride, 0.1 percent of L-lysine hydrochloride, 15mmol/L sodium dihydrogen phosphate, sodium hydroxide for adjusting the pH value to 6.8, and proper amount of water to the full amount.

2. The method according to claim 1, wherein the chromatography column has a column diameter of 50mm and a length of 12 cm.

3. A method for purifying recombinant ancrod enzyme, the method comprising the steps of:

wherein the operation of step (44) is as follows:

a chromatographic column, wherein the filler is a Heparin Sepharose6Fast Flow, the sample is the main activity peak in the step (43), the sample is diluted to 1000mL by PBS-LYS buffer solution and is loaded, and the Flow rate of the column is 2 mL/min; after loading, balancing to a baseline by using PBS-LYS buffer solution, eluting by using PBS-LYS buffer solution, and collecting active components; eluting impurity components with PBS-LYS buffer solution, washing the chromatographic column with PBS-LYS buffer solution for 1000ml, and regenerating to obtain recombinant ancrod enzyme stock solution; the PBS-LYS buffer comprises: 0.2 percent of sodium chloride, 0.1 percent of L-lysine hydrochloride, 15mmol/L sodium dihydrogen phosphate, sodium hydroxide for adjusting the pH value to 6.8, and proper amount of water to the full amount.

4. The method according to claim 3, wherein the chromatography column has a column diameter of 50mm and a length of 12 cm.

5. The method according to claim 3, wherein in step (43) a C4 preparative chromatography column is used, eluting with a gradient as shown in the following table:

time/min A B 0~50 90→30 10→70 50~60 30 70 61~71 90 10

Wherein the mobile phase A is phosphoric acid water solution with pH2.3, the mobile phase B is ethanol, the detection wavelength is 214nm, and the elution flow rate is 20 mL/min.

6. The method of claim 5, wherein 1% propylene glycol is additionally added to both mobile phase A and mobile phase B.

7. A method for preparing a recombinant ancrod injection, comprising the steps of:

(a) providing a purified recombinant ancrod stock, optionally determining the titer of the stock;

(b) diluting with PBS-LYS buffer solution, filtering with 0.22um microporous membrane for sterilization, packaging into ampoule, and sealing by melting to obtain injection; the PBS-LYS buffer comprises: 0.2 percent of sodium chloride, 0.1 percent of L-lysine hydrochloride, 15mmol/L sodium dihydrogen phosphate, sodium hydroxide for adjusting the pH value to 6.8, and proper amount of water to the full amount;

wherein:

the purified recombinant ancrod enzyme stock solution is prepared by the following method:

wherein the operation of step (44) is as follows:

chromatography column, packing is Heparin Sepharose6Fast Flow, PBS-LYS buffer solution contains: 0.2% sodium chloride, 0.1% L-lysine hydrochloride, 15mmol/L sodium dihydrogen phosphate and sodium hydroxide to adjust pH to 6.8, and adding appropriate amount of water to full volume, wherein the sample is the main active peak in step (43), diluting to 1000mL with PBS-LYS buffer solution, loading, and column flow rate is 2 mL/min; after loading, balancing to a baseline by using PBS-LYS buffer solution, eluting by using PBS-LYS buffer solution, and collecting active components; eluting with PBS-LYS buffer solution to remove impurity components, washing the column with PBS-LYS buffer solution for 1000ml, and regenerating to obtain recombinant ancrod enzyme stock solution.

8. The method according to claim 7, wherein the dilution in step (b) is performed with PBS-LYS buffer to a titer of 20 IU/mL.

9. The method of claim 7, wherein in step (44) the chromatographic column has a column diameter of 50mm and a length of 12 cm.

10. The method according to claim 7, wherein in step (43) above, a C4 preparative chromatography column is used, eluting with a gradient as shown in the following table:

time/min A B 0~50 90→30 10→70 50~60 30 70 61~71 90 10

11. The method according to claim 10, wherein 1% propylene glycol is additionally added to both mobile phase a and mobile phase B.