CN102618552B - Productive technology of recombined exenatide - Google Patents

Abstract

The invention provides a productive technology of recombined exenatide. The productive technology comprises the following steps of: completely deleting a KSI fusion protein sequence in the pET-31b(+) by transforming pET-31b(+), simultaneously deleting a cleavage site of methionine (the cleavage site of ALWN) and a histidine tage (His6-tag) of a C terminal (polypeptide carboxyl terminal) as well as a terminator, replacing by using methionine+His6-tag+GB1 mutation sequence+enterokinase cleavage sequence at the deleting position, and then constructing an engineering bacterium pET-31(b+)-Exendin-4/BL21(DE3) plays. According to the productive technology, the advantage that the pET-31(b+) can produce polypeptides on a larger scale and at high yield is used, promoters with the powerful function of the pET-31(b+) are retained, the shortcoming that a protein product is easy to form an inclusion body in other production technologies is overcome, the N terminal of an objective protein is cut by using the cutting characteristic of the enterokinase, and the cut protein is the Exendin-4 with a natural sequence. The recombined exenatide is obtained through the fermentation expression of the engineering bacterium and the purification of the objective protein. The yield of the recombined exenatide can be up to 500mg/L. Compared with the current most advanced technology, the yield is increased by 20 times, and the recombined exenatide is a soluble protein.

Description

A kind of production technique of the Exenatide of recombinating

Technical field

The invention belongs to the synthesis technical field of biological polypeptide, be specifically related to a kind of production technique of the Exenatide of recombinating.

Background technology

Diabetes are Chronic Non-Communicable Diseasess of another serious harm human health after cardiovascular and cerebrovascular diseases, tumour, and in recent years, along with the change of people life style, diabetes prevalence is sharply ascendant trend.China diabetic subject has exceeded 7,000 ten thousand at present, and diabetic subject's rate of increase is 2 times of American-European countries.Diabetes B (Type 2 Diabetes, T2DM) is the main body of diabetes, accounts for diabetic subject's 90% left and right.T2DM is interacted and is caused the secretion of pancreas islet rope or effect defect by heredity and multiple environmental factors.Its morbidity is higher, especially taking the elderly as many, and presents rejuvenation trend.Pancreas islet mouth cells reduced number or secretory functional disturbance are the key links that causes T2DM morbidity.Treatment is generally followed mode of life intervention (as dietary control, exercise therapy etc.), oral antidiabetic drug and is combined modes such as using Regular Insulin.The Side effects of pharmaceutical drugs of traditional treatment T2DM are all larger, and life-time service can excessively cause pancreas islet mouth cells nonfunction because of insulin secretion.

Glucagon-like peptide 1 (GLP1) and enendin-4 become the focus for the treatment of diabetes research in recent years.Because they have the characteristic that promotes insulin secretion in the situation that blood sugar concentration is higher, and do not play a role in orthoglycemic situation, not only can make the first diabetes B patient blood sugar recovery of controlling normal, and sulfonylurea drugs treatment inefficacy person is also had to hypoglycemic activity.

Exendin-4 is the straight-chain polypeptide of a 39 amino acid composition, is obtained at first by the saliva separation and Extraction of the huge lizard in South America.Its amino-acid residue and Mammals GLP-1 sequence have 53% homology, and biological effect also almost the maximum difference of itself and GLP-1 in full accord be dipeptidyl peptidase (DPP-IV) in the resistance to blood of glycine (Gly) of the 2nd, N end, the same position of GLP-1 is the L-Ala (Ala) for very easily being cut off by DPP-IV, therefore the transformation period that Exendin-4 is absorbed into after blood is grown (t1/2 =9.7h).Exendin-4 is a kind of potent GLP-1 receptor stimulant, can simulate the sugared regulating and controlling effect of this endogenous polypeptide of GLP-1, reduces on an empty stomach and postprandial blood sugar.The activity of Exenatide (Exenatide), mainly by mediating with human body pancreas GLP-1 receptors bind, is caused insulin synthesis and the secretion of dependence on the glucose by cyclic amp (cAMP) dependence and β mechanism of cell differentiation.Because the amino acid structure of Exendin-4 and biological activity and GLP-1 all have dependency, therefore be conventionally also regarded as the one of incretin.Because the blood sugar reducing function time of Exendin-4 is longer, delay stomach emptying and suppress to ingest to get excited the beneficial effect of adiposis patient body weight is different from again to traditional ofhypoglycemic medicine therefore its having a high potential as the exploitation of diabetes B medicine.

The drug research at present Exendin-4 being carried out is mainly preparation technology, mechanism of action, and endocrine metabolism disease is clinical, molecular pharmacology and pharmaceutics research.That the Exendin-4 medicine (Exenatide) having gone on the market adopts is the preparation technology of polypeptide synthesis.

Chemosynthesis cost high (requiring high to raw material amino acid and plant and instrument), output are few, and utilize genetically engineered to produce Exendin-4, not only can realize industrialized scale operation, effectively reduce production costs, and little to environmental influence, and product quality is safer.But with 39 such peptides of the direct Expression product Exendin-4 of gene engineering method, expression level is low, and easily degraded, can adopt the method that links amalgamation and expression with carrier proteins (as Trx etc.).But this method also exists the desired polypeptides molecule proportion in fusion protein molecule very little, and output is very low, and after fusion rotein cracking, polypeptide kind is a lot, the problem of separation and purification difficulty.The method of the expression product of effective increase gene is to build gene concatermer, according to the characteristic of the feature of target gene and expression product, use suitable molecular biology operative technique that goal gene is cascaded in a certain way, be placed under the control of expression vector promotor and express, again by specific material for concatermer product (enzyme or the chemical reagent) cracking of expressing, to obtain target peptide monomer.Such as pET-31b(+) be the plasmid of a conventional production polypeptide, but it is used for producing polypeptide, design was easily by the proteolysis enzymic hydrolysis in intestinal bacteria body for fear of polypeptide originally, so allow desired polypeptides express together with KSI fusion rotein, form inclusion body, this is a very large shortcoming to producing Exendin-4, can cause the raising greatly of purifying cost and active being difficult to recover if allow Exendin-4 first generate inclusion body repeatability, this has been the bottleneck of the industrialization production of restructuring Exenatide.

Summary of the invention

The object of the invention is to solve the above-mentioned technical problem existing in prior art, a kind of production technique of the Exenatide of recombinating is provided.

For achieving the above object, the technical solution used in the present invention is as follows:

The production technique of restructuring Exenatide of the present invention, comprises structure, the fermentation expression of engineering bacteria and the purifying of target protein of engineering bacteria, and the structure of described engineering bacteria carries out in the steps below:

(1) synthetic of restructuring Exendin-4 polypeptide gene sequence: according to e. coli codon preferences, the nucleotide sequence of design coding Exendin-4, transform the goal gene as shown in SEQ ID No.1 as;

(2) MAG2010 plasmid: get pET31b (+) plasmid, cut away KSI fusion gene fragment shown in SEQ ID No.2, be replaced by the gene shown in SEQ ID No.3, removing restrictions property restriction endonuclease AlwnI restriction enzyme site and methionine(Met) and successive sequences, replace the gene with enteropeptidase restriction enzyme site and target protein, cut away histidine mark sequence, before GB1 albumen, add histidine mark, add two terminators at the C-terminal of target protein; The plasmid sequence building is: methionine(Met) encoding sequence+6XHis-tag encoding sequence+GB-1 encoding sequence+enteropeptidase restriction enzyme site encoding sequence+and gene+glycine coding+bis-terminators of target protein;

(3) structure of engineering bacteria: the gene fragment obtaining according to the order of the two terminator codons of the cracking site-exedin-4-of promotor-6X Histidine-GB1-tag-enteropeptidase, utilize CloneEZ test kit to be connected in the MAG2010 plasmid of well cutting, obtain recombinant plasmid pET-31 (b+)-Exendin-4, by recombinant plasmid pET-31 (b+)-Exendin-4 with CaCl ₂method transforms and is subject to thalline BL21 (DE3) plays, at 37 DEG C, in LB substratum, cultivate, collect thalline, screening positive clone, as engineering bacteria pET-31 (b+)-Exendin-4/ BL21 (DE3) plays of restructuring Exendin-4 amalgamation and expression.

Make biosynthesizing Exendin-4 can expand large-scale production application, one of crucial is to optimizing fermentation, maximum possible utilize bacterial strain Exendin-4 high yield ability, produce in most economical mode.

In general, while producing soluble proteins, can not adopt the method for high density fermentation, because so easy formation inclusion body, the substratum utilizing both at home and abroad is at present mostly 2XYT substratum or LB substratum is cultivated, utilization be the fask oscillating method cultivation of research laboratory in mostly.

The fermentation expression of engineering bacteria of the present invention comprises the steps:

(1) choose single bacterium colony to being equipped with in 30 mL target substratum, 31 DEG C, 200rpm activation is spent the night;

(2) 30mL bacterium liquid is received in 200 mL 2XYT substratum, 32 DEG C, 200rpm cultivates approximately 2.6 hr;

(3) with 10% inoculum size, receive in 5 L MMBL substratum, 32 DEG C, 240rpm cultivates approximately 3 hr;

(4) receive in 60 L fermention mediums;

(5) control pH in vegetative period is 6.8; Make DO>=10% with stirring velocity and air flow; When the concentration of glucose is down to 0.2g/L in substratum, start feed supplement; Work as OD ₅₅₀while reaching 10 left and right, add 13 mL 1M IPTG inductions, final concentration is 0.2mM, and pH is slowly adjusted to 7.00, continues to cultivate after 10 hours and finishes.

The purification step of described target protein adopts the affinity chromatography of ion exchange chromatography-column chromatography-sandwich type to separate and purifying; This project bacterium by fermentation, the output of the restructuring Exenatide that obtains of purifying reaches the productive rate of 500 mg/litre.

The affinity chromatography of described sandwich type comprises affinity chromatography one, enzymatic lysis and affinity chromatography two, and concrete steps are as follows:

(1) affinity chromatography one: the IgG-sepharose-fast flow column that adopts GE company, first use 50 mM Tris of 3 column volumes, pH 7.5, the damping fluid balance pillar of 150 mM NaCI, then use the protein upper prop of dialysing by same buffer, wash and then use 5mM sodium acetate with 1 times of above-mentioned damping fluid of volume, the damping fluid of pH5.0 washes away unconjugated impurity, then use 500mM sodium acetate, the damping fluid of pH5.0 elutes target protein, collect, concentrated, with enough 20mM Tris-HCl, 100mM NaCl, pH7.6 dialysis 12 hours,

(2) enteropeptidase processing: the Bovine Enterokinase Light Chain in Recombinant subunit of 1 μ l is at 20 DEG C, 20mM Tris-HCl, 100mM NaCl, 8h cleavage of fusion proteins completely under the condition of pH7.6;

(3) affinity chromatography two: the restructuring Exendin-4 of above-mentioned processing is combined on nickel post, first rinses dephosphorylation salt buffer with initial damping fluid, retain elution fraction, concentrated, lyophilize, obtains the Exenatide of recombinating.

Because Exenatide is a polypeptide that molecular weight is smaller, and be not suitable for expressing by the system of high molecular weight protein, so we adopt and are used for specially improved production expression of polypeptides system: pET-31b(+) plasmid and E. Coli (DE3) PlyS produce, adopt this individual system to have following advantage: pET-31b(+) be a plasmid of producing polypeptide, desired polypeptides is expressed together with KSI fusion rotein, form inclusion body, can avoid the polypeptide of producing by the proteolysis enzymic hydrolysis in intestinal bacteria body, but this is a very large shortcoming to producing Exendin-4, if the form and then the renaturation that allow Exendin-4 first generate inclusion body can cause greatly improving of purifying cost and active being difficult to recover, so we are to pET-31b(+) transform, by pET-31b(+) in KSI fusion rotein sequence delete completely, delete methionine(Met) cracking site (ALWN cleavage site) and C-terminal (polypeptide carboxyl terminal) histidine mark (His simultaneously ₆-tag) and terminator, in the position of deleting, replace with methionine(Met)+His ₆-tag+GB1 mutant nucleotide sequence+enteropeptidase cleavage sequence, we by transformation pET-31b(+) form novel plasmid rename as Mag2010, there is this plasmid, first we obtain the original series of Exendin-4, then transform for the preference of genetic codon according to intestinal bacteria, adopt the genetic sequence that is applicable to escherichia coli expression, the complete sequence of the Exendin-4 of synthetic transformation, then clone in the PUC57 plasmid of island and increase on a large scale, by the cutting of Exendin-4 sequence purifying after amplification, then be cloned in the Mag2010 plasmid of reincarnate, and add dual terminator at C-terminal, the benefit of so doing be utilized pET-31b (+) itself can be extensive, the advantage of the production polypeptide of high yield, retain its powerful promotor, overcome the shortcoming that this plasmid easily forms inclusion body, utilize the cutting characteristic of enteropeptidase to cut at the N-terminal of target protein, protein after cutting is the Exendin-4 with native sequences completely.Utilize the reason of intestinal bacteria E.Coli BL21 (DE3) PlyS expression system to be that Exendin-4 does not need the glycosylation modified posttranslational modification of Denging, when transcribing, DNA do not need post transcriptional modificaiton yet, so be particularly suitable for producing with Escherichia coli system, add us and overcome the problem that forms inclusion body, and the advantage of E.Coli BL21 (DE3) PlyS be can mass expressing external albumen, and the interference of the toxin such as resistance to foreign protein.

The present invention has Exenatide the possibility of 90% formation inclusion body to become 90% formation soluble proteins by connecting GB1 mark fusion rotein.Experiment showed, that the Exenatide of overwhelming majority restructuring generation is all in soluble protein.

In the system that the Exenatide at home and abroad carrying out is expressed, a lot of people have adopted His ₆-Thioredoxin A (TrxA) fusion rotein and Exendin-4 carry out amalgamation and expression, fusion protein molecule amount is 14.7+4.2=18.9kd, the ratio of exendin in fusion rotein be 4.2/18.9=22.2%. we adopted the GB1 of self molecular weight and Exendin-4 to carry out amalgamation and expression, fusion protein molecule amount is 14.7+4.2=18.9kd, and the ratio of exendin in fusion rotein is 4.2/11.9=35.3%.That is to say, the proportion of Exendin-4 in fusion rotein has increased greatly, under similar system, if the fusion rotein total amount of expressing equate, exendin-4 output in our system is 1.59 times of other systems so.

The present invention adopts the system of GB1 and His-tag double-tagging to make in purge process, both to have adopted affinity chromatography, can adopt again GB1 affinity chromatography, with respect to other purification process, can have more purifying selection mode.

In existing bibliographical information, output is very low, maximum namely output of 28 mg/litre; utilize fermentation system of the present invention; we can reach the productive rate of 500 mg/litre, and 20 times of left and right that this output is current zymotechnique, so can greatly reduce costs after large-scale production.Reduce and medicine universal has meaning difficult to the appraisal for the medicine cost value of Exenatide class, just as having important social value and economic worth after recombinant human insulin succeeds in developing for the popularizing of Regular Insulin.

Production technique of the present invention has outstanding feature with respect to current technique: more than output can reach 500mg/ liter, 20 times are improved than current state-of-the-art process yields, and be soluble proteins, in process of production, we adopted our company's uniqueness have independent intellectual property right zymotechnique, output improves greatly, the dual affinity purification technique that we adopt, coordinate traditional purification process, purification efficiency is greatly improved, early stage is the purifying of extraction slightly, has alleviated the pressure of follow-up purifying, has reduced the cost of purifying.

Brief description of the drawings

Growth curve of bacteria figure in Fig. 1 fermenting process.

Fig. 2 is Fermentation Process of Parameter monitoring result figure.

Fig. 3 is the stability analysis result figure of plasmid.

Fig. 4 is that the cell of plasmid includes spirogram.

Fig. 5 is the detected result figure of active cells.

Fig. 6 is polyacrylamide gel electrophoresis figure.

Embodiment

Below in conjunction with embodiment, the present invention is elaborated.

One, the structure of engineering bacteria

(1) synthetic of restructuring Exendin-4 polypeptide gene sequence: according to e. coli codon preferences, the nucleotide sequence of design coding Exendin-4, transform the goal gene as shown in SEQ ID No.1 as; Gene clone after synthetic is entered in plasmid PUC57, is transformed in bacillus coli DH 5 а and increases, and then carries out purifying with the plasmid extraction kit of EZ Bioresearch company, and it is for subsequent use that the goal gene after cutting goes out purifying.

(2) MAG2010 plasmid: MAG2010 plasmid: get pET31b (+) plasmid, cut away KSI fusion gene fragment shown in SEQ ID No.2, be replaced by the gene shown in SEQ ID No.3, removing restrictions property restriction endonuclease AlwnI restriction enzyme site and methionine(Met) and successive sequences, replace the gene with enteropeptidase restriction enzyme site and target protein, cut away histidine mark sequence, before GB1 albumen, add histidine mark, add two terminators at the C-terminal of target protein; The plasmid sequence building is: methionine(Met) encoding sequence+6XHis-tag encoding sequence+GB-1 encoding sequence+enteropeptidase restriction enzyme site encoding sequence+and gene+glycine coding+bis-terminators of target protein.

(3) structure of engineering bacteria: the gene fragment obtaining according to the order of the two terminator codons of the cracking site-exedin-4-of promotor-6X Histidine-GB1-tag-enteropeptidase, utilize CloneEZ test kit to be connected in the MAG2010 plasmid of well cutting, obtain recombinant plasmid pET-31 (b+)-Exendin-4, by recombinant plasmid pET-31 (b+)-Exendin-4 with CaCl ₂method transforms and is subject to thalline BL21 (DE3) plays, at 37 DEG C, in LB substratum, cultivate, collect thalline, screening positive clone, as engineering bacteria pET-31 (b+)-Exendin-4/ BL21 (DE3) plays of restructuring Exendin-4 amalgamation and expression.

Subclone plasmid used is purchased from Novagen company of the U.S., bacillus coli DH 5 а and BL21 (DE3) PlyS is respectively purchased from Beijing company of Suo Laibao bio tech ltd and red autumnal leaves bio tech ltd, restriction enzyme used is purchased from Dalian precious biological (Takara), enteropeptidase is purchased from company of Sigma of the U.S. (Sigma), and plasmid extraction kit adopts the U.S. EZ Bioresearch plasmid extraction kit in a small amount of our company's sale.

Two, the fermentation expression of engineering bacteria

1, seed activation:

(1) seed activation: get frozen engineering bacteria line containing on the LB agar plate of 100ul/ml penbritin, cultivate 16 hours for 37 DEG C.Select well-grown single bacterium colony, be inoculated in (containing Amp100ul/ml) in 20ml LB nutrient solution 37 DEG C of overnight incubation.

(2) seed liquor preparation: get activated seed, be inoculated in (containing Amp100ul/ml) in 200ml 2XYT nutrient solution by 5% inoculum size, cultivate 6 hours for 37 DEG C.

(3) 5L ferment tank: seed liquor is inoculated in by 5% inoculum size in the fermentor tank that MMBL substratum is housed, 37 DEG C, control pH in 7.0 left and right, by ventilation and rotating speed control dissolved oxygen 30%.When OD600 is 20 left and right, add IPTG to final concentration be 0.2mM, induce after 10 hours lower tank.Centrifugal, collect thalline.

2, culture medium prescription

(1) L Bliquid nutrient medium (one-level shaking flask)

(2)mMBL liquid nutrient medium (secondary medium)

3, fermentative production step:

(1) choose single bacterium colony to being equipped with in 30 mL target substratum, 31 DEG C, 200rpm activation is spent the night.30mL bacterium liquid is received in 200 mL 2XYT substratum, and 32 DEG C, 200rpm cultivates approximately 2.6 hr.

(2) with 10% inoculum size, receive in 5 L MMBL substratum, 32 DEG C, 240rpm cultivates approximately 3 hr.

(3) receive in 60 L fermention mediums.

(4) control pH in vegetative period is 6.8; Make DO >=10% with stirring velocity and air flow; When the concentration of glucose is down to 0.2g/L in substratum, start feed supplement.Work as OD ₅₅₀while reaching 10 left and right, add 13 mL 1M IPTG inductions (final concentration is 0.2mM), pH is slowly adjusted to 7.00, continue to cultivate after 10 hours and finish.

Fermentation record sees the following form

Experimental result:

Growth curve of bacteria figure in Fig. 1 fermenting process.4ml MMBL substratum is poured in cuvette, select on 550nm wavelength spectrophotometer and regulate zero point, as blank, and different time nutrient solution is measured successively from 0h, the bacteria suspension that concentration is large is suitably measured after dilution with fresh MMBL liquid nutrient medium, make its OD value in 0.10.～0.65, the OD value recording after dilution will be multiplied by extension rate, is the OD value of nutrient solution reality.

Fermentation Process of Parameter monitoring result is shown in Fig. 2.(1) temperature: be set as 32 DEG C, in fermenting process, have slight fluctuations (2) rotating speed: initial speed setting is 250rpm, rotating speed and dissolved oxygen interlock, in the time that dissolved oxygen is reduced to setting Schwellenwert, rotating speed starts to increase, to ensure that the dissolved oxygen concentration in fermentor tank maintains finite concentration.(3) pH: after fermentor tank sterilizing, pH is 7.15, is adjusted into 6.8 before inoculation, fermentation is IPTG induction when 5hr, pH bottom out, control pH between 7.2～7.3 until fermentation ends.(4) dissolved oxygen: fermentation arranges dissolved oxygen >=10, with rotating speed and ventilation interlock, in the time that dissolved oxygen is down to Schwellenwert, ventilation increases, and rotating speed starts to increase, to maintain dissolved oxygen concentration.

The stability analysis of plasmid the results are shown in Figure 3.By the single bacteria culturing cell dilution 10 that contains plasmid ⁶doubly, get 10 milliliters of cultivations, until cell concn is 10 ⁸cFU/ml, and then with fresh substratum dilution 10 ⁴-10 ⁶doubly, repeat above operation until cell completes the unsaturation growth of 200 generations, in order to ensure that cell is always in logarithmic phase growth, the concentration of cell is carried out monitoring growth with OD600, and determines with plate count.In each dilution point, the culturing cell bed board of dilution is (containing 5-bromo-4-chloro-3-indolyl β-D-galactoside) on LBH agar plate, uses with blue Lac ⁺and white white Lac (plasmid-containing) (plasmid-free) carry out the difference of comparison quantity, the quantity of passage also can be used for identifying the stability of plasmid simultaneously.

The cell intensive amount of plasmid is shown in Fig. 4.For the content of plasmid in aspect textual criticism cell from the side, by centrifugal the fermented liquid of each time point, obtain thalline, utilize plasmid extraction kit in a small amount to carry out plasmid extraction, the plasmid that extracting obtains detects on 1% Agar glue, within 10 hours, in inner cell, contains enough plasmids and express the mRNA of desirable proteins.

The detected result of active cells is shown in Fig. 5.By centrifugal the fermented liquid of each time point, obtain thalline, utilize cell counter to detect under the microscope, then bed board carries out flat board cultivation, and the result that cultivation obtains and the result difference of microscopic examination relatively can obtain dead cell number.

Three, the purifying of target protein

Utilize continuous flow centrifuge to carry out centrifugation (8000rpm) fermented liquid after 60L fermentation, obtain 5000g bacterial sediment, abandon supernatant.Gained for thalline phosphate buffered saline buffer (pH=7.4) clean 3 times, the thalline after cleaning carries out fragmentation.

Crushing process 1: ultrasonic disruption:

Power 60%, works 3 seconds, 3 seconds, interval, and 300 circulations, until ultrasonic liquid becomes clear, centrifugal 10,000 rpm 10 minutes, removes precipitation (not broken cell, cell walls etc.), obtained component detects analysis by SDS-PAGE.

Crushing process 2: cryogenic high pressure fragmentation

Adopt JN-3000 low-temperature ultrahigh-pressure continuous flow cell crusher, by continuous flow centrifuge and the fragmentation of JN-3000 low-temperature ultrahigh-pressure continuous flow cell with coupling, can solve microorganism collection, cell debris after cytoclasis-removal fragmentation, collect the full-automation of the operating process of supernatant (containing soluble protein), greatly save manpower, and the time.The key technical indexes: pressure 200MPa Continuous Flow 35ml/ divides the broken whole process of (2.1 ls/h) power supply 220V 1.5KW to carry out in water bath, on the rocks.

Fig. 6 is polyacrylamide gel electrophoresis figure.From fermentor tank, sample 20 microlitres, add respectively 2X sample-loading buffer, incubated at room 30 minutes, loading, in Bole Mini-3 electrophoresis, carrying out gel electrophoresis, there is obvious band near being presented at molecular weight 11.92 in result, conforms to the target protein molecular weight of expection.

The processing of nucleic acid impurity:

Add the DNase of 20mg/L, the RNase nucleic acid that is hydrolyzed, hydrolysis temperature is 37 DEG C, incubation time is 30min.

Ammonium sulfate precipitation:

Then supernatant after treatment crusher nuclease is carried out to fractionation precipitation with gradient ammonium sulfate: the consumption that slowly adds required ammonium sulfate in constantly stirring, the concentration of ammonium sulfate is respectively (20%, 40%, 60%, 80%), by the restructuring Exendin-4(40-80% after precipitation) again in dissolving phosphoric acid salt buffer (pH=7.4).

Ion exchange chromatography:

Get the cationic exchange coloum QSHP(GE Healthcare of 5 kilograms of GE Healthcare life science), dress post, first use 5 column volumes of phosphate buffered saline buffer (pH=7.4) wash-out, then the phosphoric acid buffer (pH=7) that adopts the sodium-chlor that contains different concns (0.1M-0.5M), carries out gradient elution (3 column volume/damping fluids.Obtained component detects analysis by SDS-PAGE.

Column chromatography:

Feature according to the molecular weight of Exendin-4 fusion rotein at～12 KD, the fusion rotein that wash-out is obtained utilizes cut stream concentrated, upper prop, adopt the GE Healthcare life science molecular sieve Sephadex G-50 medium of 5KG further to separate, adopt the phosphate buffered saline buffer (50mM of 15L, pH=7) carry out damping fluid, elution volume is 3 column volumes.

Amidation: the enzyme of employing is restructuring glycine amidation monooxygenase, adopt reaction system, 100 mM TES (N-tris[hydroxymethyl] methyl-2-aminoethane sulfonic acid), 4.7 μ M cupric ions, 5.5mM vitamins C damping fluid, 1mU/ml glycine amidating enzyme, pH 7.0, temperature of reaction is 37 ° of C. reaction times: 3 hours.

Affinity chromatography technique one: the IgG-sepharose-fast flow column (GE Healthcare) that adopts GE company, first use 50 mM Tris of 3 column volumes, pH 7.5, the damping fluid balance pillar of 150 mM NaCI, then use the protein upper prop of dialysing by same buffer, wash and then use 5mM sodium acetate with 1 times of above-mentioned damping fluid of volume, the damping fluid of pH5.0 washes away unconjugated impurity, then use 500mM sodium acetate, the damping fluid of pH5.0 elutes target protein, collect, concentrated, with enough 20mM Tris-HCl, 100mM NaCl, pH7.6 dialysis 12 hours.Prepare enzymic hydrolysis.

Enteropeptidase processing:

The Bovine Enterokinase Light Chain in Recombinant subunit of 1 μ l is at 20 DEG C, 20mM Tris-HCl, 100mM NaCl, 8h cleavage of fusion proteins completely under the condition of pH7.6.

Affinity chromatography technique two: the restructuring Exendin-4 of above-mentioned processing is combined on nickel post, first rinses dephosphorylation salt buffer (50mM, pH=7) with initial damping fluid, retain elution fraction, concentrated, lyophilize, obtains the Exenatide of recombinating.After above-mentioned handling, adopt and increase the method for imidazole concentration (0.1-0.5M) in damping fluid in connection with the histone-GB1 fusion rotein wash-out on pillar out, clean pillar and it is regenerated to specifications.

Desalination and enteropeptidase impurity:

Desalination process 1:

Feature according to the molecular weight of Exendin-4 albumen at～4.2 KD, the target components that wash-out is obtained is concentrated, upper prop, adopt GE Healthcare life science molecular sieve Sephadex G-25 medium further to separate, utilize phosphate buffered saline buffer (50mM, pH=7) carry out damping fluid, desalination.

Desalination process 2:

Take the mode of cut stream ultrafiltration to carry out desalination.The molecular weight of Exendin-4 albumen, at～4.2 KD, is relatively applicable to ultrafiltration desalination and concentrated, similar to general ultra-filtration process.Main investigation working pressure, operating time and the impact of feed velocity on ultra-filtration process, for production process provides technical matters parameter

The mensuration of Exendin-4 content:

Adopt BCA determination of protein concentration test kit (BCA Protein Assay Kit) (Thermo Scientific Pierce, the U.S.), operation steps is carried out the mensuration of protein content to specifications.Result shows, output 1. BCA working fluids preparations: quantity per sample, adds 1 volume BCA reagent B(50:1 by 50 volume BCA reagent A) prepare appropriate BCA

Working fluid, fully mixes.

2. get as required appropriate BSA protein standard, add deionized water to be diluted to 1mg/ml(stoste 5mg/ml), and mix.

Attention: protein sample is in what solution in principle, and what solution dilution standard substance also should use.But for for simplicity, also can use

Deionized water, 0.9%NaCl or PBS dilution standard product.Protein standard substance after dilution also can-20 DEG C long-term preservations.In following steps, all acquiescence adopts deionized water, can be according to condition choice for use diluent.

3. Specification Curve of Increasing: get 8 cuvettes and be numbered respectively A-H, add reagent by following list data: (this scheme work linearity range is 50-1000ug/ml.）

Final volume 1200ul

4., after vibration mixes, place 30 minutes for 37 DEG C.

5. with the light absorption value at spectrophotometric determination 562nm place, taking the absorbance value that do not contain BSA as blank.

6. taking protein content, (μ is g) as X-coordinate, and light absorption value is ordinate zou, draws typical curve.

7. sample determination: testing protein sample is diluted to proper concn with deionized water, gets 100 μ l samples, add 1000 μ l BCA

Working fluid, mixes latter 37 DEG C and places 30 minutes, then taking A cuvette as contrast, and working sample absorption value A562.

8. according to the absorption value recording, on typical curve, can check in the protein content of sample.

The productive rate of Exenatide is about 500mg/L fermented liquid.

<110> Dongguan Maigen Biological Science and Technology Co., Ltd.

The production technique of a <120> Restruction Exenatide

<160> 3

<210> 1

<211> 117

<212> DNA

<213> artificial sequence

<220>

<222> （1）…（117）

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<210> 2

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<212> DNA

<213> artificial sequence

<220>

<222> （1）…（394）

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gatctgggta ccgacgacga cgacaaggcc atggcgatat cggatccgaa ttcgagctcc 360

gtcgacaagc ttgcggccgc actcgagcac caccaccacc accactgaga tccg 394

<210> 3

<211>

<212> DNA

<213> artificial sequence

<220>

<222> （1）…（204）

<400>3

atgcaccatc atcatcatca catgcagtac aaggtcatcc tgaacggcaa gacgctgaaa 60

ggcgaaacga cgacggaagc agtggacgcg gccaccgcag aaaaagtggt taagcagttt 120

ttcaacgata atggcgtcga cggtgaatgg acgtatgatg acgctaccaa aacgtttacc 180

gtgacggaag atgacgatga caag 204

Claims (1)

1. the recombinate production technique of Exenatide, comprises and it is characterized in that structure, the fermentation expression of engineering bacteria and the purifying of target protein of engineering bacteria:

The structure of described engineering bacteria carries out in the steps below:

(1) synthetic of restructuring Exendin-4 polypeptide gene sequence: according to e. coli codon preferences, the nucleotide sequence of design coding Exendin-4, transform the goal gene as shown in SEQ ID No.1 as;

(2) MAG2010 plasmid: get pET31b (+) plasmid, KSI fusion rotein sequence in pET31b (+) is deleted completely, delete methionine(Met) cracking site and C-terminal histidine mark and terminator simultaneously, in the position of deleting, replace with methionine(Met)+His ₆-tag+GB1 sequence+enteropeptidase cleavage sequence, the novel plasmid that the pET31b (+) of transformation is formed renames as Mag2010;

(3) structure of engineering bacteria: by the cutting of Exendin-4 sequence purifying after amplification, then be cloned in the Mag2010 plasmid of reincarnate, and add dual terminator at C-terminal, obtain recombinant plasmid pET31b (+)-Exendin-4, by recombinant plasmid pET31b (+)-Exendin-4 with CaCl ₂method transforms and is subject to thalline BL21 (DE3) plys, at 37 DEG C, in LB substratum, cultivate, collect thalline, screening positive clone, as engineering bacteria pET31b (+)-Exendin-4/ BL21 (DE3) plys of restructuring Exendin-4 amalgamation and expression;

The fermentation expression of described engineering bacteria comprises the steps:

(1) choose single bacterium colony to being equipped with in 30 mL target substratum, 31 DEG C, 200rpm activation is spent the night;

(2) 30mL bacterium liquid is received in 200 mL 2XYT substratum, 32 DEG C, 200rpm cultivates approximately 2.6 hr;

(3) with 10% inoculum size, receive in 5 L MMBL substratum, 32 DEG C, 240rpm cultivates approximately 3 hr;

(4) receive in 60 L fermention mediums;

(5) control pH in vegetative period is 6.8; Make DO>=10% with stirring velocity and air flow; When the concentration of glucose is down to 0.2g/L in substratum, start feed supplement; Work as OD ₅₅₀while reaching 10 left and right, add 13 mL 1M IPTG inductions, final concentration is 0.2mM, and pH is slowly adjusted to 7.00, continues to cultivate after 10 hours and finishes.