Polypeptide with high biological activity and application thereof

Abstract

The invention provides a polypeptide with high biological activity and application thereof, and relates to the technical field of active peptide preparation. According to the method, the polypeptide with high biological activity is obtained by performing enzymolysis on the abalone. The obtained polypeptide is analyzed and screened to obtain the polypeptide with high biological activity, wherein the amino acid sequence of the polypeptide is shown as SEQ ID NO.1-9. The polypeptide disclosed by the invention has relatively high biological activity, the polypeptide with the amino acid sequence shown as SEQ ID NO.1-9 has relatively high angiotensin converting enzyme inhibition property, and IC50 (50% of IC50) on angiotensin converting enzyme is 0.15-0.37 mg / mL, so that the activity of the angiotensin converting enzyme can be relatively well inhibited; in addition, the polypeptide provided by the invention also has oxidation resistance. Therefore, the polypeptide provided by the invention effectively improves the condition of low polypeptide biological activity in industrial production, and provides technical support and supplement for preparation and screening of marine bioactive peptides.

Description

Technical Field

[0001] The present invention relates to the technical field of active peptide preparation, and in particular to a polypeptide with high biological activity and its application. Background Art

[0002] With the development of the economy, people's requirements for the quality of life have gradually increased, and their awareness of health has gradually improved. Therefore, people's consumption of health products has gradually increased. As a functional food, bioactive peptides play an indispensable role in people's daily life because they not only have rich nutritional value but also have various physiological functions such as antioxidant, anti-cancer, antibacterial, blood pressure lowering, and immune regulation. Bioactive peptides are diverse in types and wide in sources. They can be obtained from the proteins of animals and plants. Plant protein sources include legumes, grains, etc., and animal sources include milk, meat products, eggs, etc.

[0003] Abalone is a marine gastropod, a single-shell mollusk, and is deeply loved by consumers. As an important marine product, the market price of abalone is lower than that of high-grade and precious economic fish, but their nutritional value is not inferior, and they have high edible and medicinal values. Abalone is rich in protein, polysaccharides, taurine, and trace elements. The collagen content in its peptide products is also as high as 30%-50%, far higher than that of other fish and shellfish. At the same time, the contents of taurine, selenium, etc. in abalone are much higher than those of common marine shellfish such as mussels, oysters, and clams, making it a good resource for developing marine bioactive peptides. Currently, the most commonly used method for preparing bioactive peptides is enzymatic hydrolysis, and the main enzymes used are non-specific enzymes such as alkaline protease, neutral protease, trypsin, papain, etc. The components of the obtained products are relatively complex, resulting in low biological activity. Therefore, there is still a lack of research on how to obtain polypeptides with high biological activity. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the problem of the lack of a polypeptide with high biological activity in the prior art.

[0005] To solve the above technical problem, the present invention provides a polypeptide with high biological activity and its application. The present invention screens a polypeptide with high biological activity from the enzymatic hydrolysate by enzymatically hydrolyzing abalone. The amino acid sequence of the polypeptide of the present invention is shown in SEQ ID NO.1-9, and the polypeptide of the present invention has high biological activity. First, the polypeptide of the present invention has high angiotensin-converting enzyme inhibitory activity, and the IC 50 of the angiotensin-converting enzyme is between 0.15-0.37 mg / mL, so it can better inhibit the activity of angiotensin-converting enzyme; in addition, the polypeptide of the present invention also has antioxidant activity, and the EC + against ABTS· 50It is between 0.12 - 1.08 mg / mL. The polypeptide provided by the present invention effectively improves the low bioactivity of polypeptides in industrial production, and at the same time provides technical support and supplement for the preparation and screening of marine bioactive peptides.

[0006] The first object of the present invention is to provide a polypeptide with high bioactivity, and the amino acid sequence of the polypeptide is shown as any one of SEQ ID NO.1 - 9.

[0007] Further, SEQ ID NO.1: SYPPLGRF;

[0008] SEQ ID NO.2: WGDHGW;

[0009] SEQ ID NO.3: SSYPPLGRF;

[0010] SEQ ID NO.4: WPNRPP;

[0011] SEQ ID NO.5: WSDRIPF;

[0012] SEQ ID NO.6: GWDKFWPE;

[0013] SEQ ID NO.7: PDRPW;

[0014] SEQ ID NO.8: FYDHIF;

[0015] SEQ ID NO.9: ADWDFLPAK.

[0016] Further, the polypeptide is prepared through the following steps:

[0017] S1. Add a non-specific enzyme to the abalone extract for reaction to obtain a crude extract;

[0018] S2. Add a mixed enzyme containing prolyl endopeptidase, chymotrypsin and proteinase K to the crude extract for reaction, and screen to obtain the polypeptide.

[0019] Further, the non-specific enzyme includes papain, neutral protease, alkaline protease, trypsin and lipase, and the mass ratio of papain: neutral protease: alkaline protease: trypsin: lipase is 1:2:2:2:1.

[0020] Further, the abalone extract in step S1 is obtained by heating and pulverizing abalone, wherein the heating temperature is 110 - 130 °C and the heating time is 4 - 6 hours.

[0021] Further, the temperature of the reaction in step S1 is 40°C - 60°C, and the pH of the reaction is 6.5 - 7.5.

[0022] Further, in step S1, a non-specific enzyme is added to the abalone extract for reaction. After the reaction is completed, enzyme inactivation treatment is carried out. After centrifugation, the supernatant is taken to obtain the crude extract. Among them, the enzyme inactivation treatment is to heat the abalone extract after the reaction is completed to 90 - 95°C, and the heating time is 10 - 15 minutes.

[0023] Further, the mass ratio of prolyl endopeptidase: chymotrypsin: proteinase K is (1 - 2):(1 - 2):(1 - 2).

[0024] Further, the mass ratio of the mixed enzyme to the crude extract is (1 - 3):100.

[0025] The second object of the present invention is to provide a gene encoding the above polypeptide.

[0026] The third object of the present invention is to provide an application of the above polypeptide in the preparation of antihypertensive products.

[0027] The fourth object of the present invention is to provide an application of the above polypeptide in the preparation of antioxidant products.

[0028] Beneficial effects of the present invention:

[0029] The present invention provides a polypeptide with high biological activity and its application. The present invention uses multiple enzymes to carry out stepwise enzymatic hydrolysis on abalone, and the obtained polypeptide solution has high biological activity. Polypeptides with amino acid sequences shown in SEQ ID NO.1 - 9 are screened and identified from the polypeptide solution. The polypeptide of the present invention has high biological activity. First of all, the polypeptide of the present invention has high angiotensin-converting enzyme inhibitory activity, and the IC 50 of the angiotensin-converting enzyme is between 0.15 - 0.37 mg / mL, so it can better inhibit the activity of angiotensin-converting enzyme; in addition, the polypeptide of the present invention also has antioxidant properties, and the EC + against ABTS· 50 is between 0.12 - 1.08 mg / mL. The polypeptide provided by the present invention effectively improves the situation of low biological activity of polypeptides in industrial production, and at the same time provides technical support and supplement for the preparation and screening of marine bioactive peptides. Description of the drawings

[0030] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to the specific embodiments of the present invention in combination with the drawings, wherein

[0031] Figure 1It is the flow chart of the polypeptide preparation technical route of the present invention;

[0032] Figure 2 It is the schematic diagram of Sephadex G-15 gel filtration chromatography and fraction collection of the present invention;

[0033] Figure 3 It is the result diagram of ACE activity determination of the fractions in the gel filtration sequence of the present invention. Detailed implementation manners

[0034] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the specific embodiments cited are not intended to limit the present invention.

[0035] Non-specific enzymes: Papain (>200000u / g) is provided by Shenzhen Xiament Biotech Co., Ltd., China; Neutrase (>2.4AU-A / g), Alcalase (>6.5AU-N / g) are from Novozymes (China) Biotech Co., Ltd.; Trypsin (>250000u / g) is from Shanghai Macklin Biochemical Co., Ltd., China, and the product number is T992772-100mg; Lipase (>30000u / g) is from Shanghai Yuanye Bio-Technology Co., Ltd., China. The mass ratio of papain: Neutrase: Alcalase: Trypsin: Lipase is 1:2:2:2:1.

[0036] Detection method of ACE inhibitory (ACEi):

[0037] Using FAPGG as the substrate (FAPGG: N-[3-(2-furyl)acryloyl]-L-phenylalanyl-glycyl-glycine, FAPGG is a common substrate of angiotensin converting enzyme (ACE) and is often used for in vitro quantitative determination of the activity of angiotensin converting enzyme), add reactants in the enzyme-linked immunosorbent assay (ELISA) plate according to the table. With the help of an enzyme-linked immunosorbent assay reader, measure the absorbance A1 before the reaction at 340nm, and then measure the absorbance value A2 after incubation at 37°C for 30min, calculate ΔA, ΔA = A1 - A2, and express the ACE enzyme activity as the change in absorbance value per unit time. The calculation of the ACE inhibition rate is as follows:

[0038] ACE inhibition rate (%) = 1 - ΔA sample / ΔA blank × 100%

[0039] In the formula: ΔA blank is the change in absorbance within 30min when adding buffer; ΔA sample is the change in absorbance within 30min when adding inhibitor.

[0040] ABTS· + Detection method of scavenging rate:

[0041] ABTS·+ The working solution was prepared by mixing an ABTS solution (7.0 mM) with an equal volume of a potassium persulfate solution (2.45 mM), incubating in the dark at room temperature for 12 - 16 h, and diluting with a 50% ethanol solution to an absorbance of 0.75 - 0.80 at a wavelength of 734 nm. 200 μL of the ABTS· + working solution was added to 10 μL of the sample, incubated in the dark at room temperature for 30 min, and the absorbance at 734 nm was measured. PBS buffer was used instead of the sample as a control. ABTS· + The calculation of the scavenging rate (%) is as follows:

[0042] ABTS· + Scavenging rate (%) = (Ablank - Asample) / Ablank × 100%

[0043] Example 1

[0044] (1) After heating and steaming abalone at 115 °C for 4.5 h, water was added and mixed evenly. After crushing with a crusher, an abalone extract was obtained; the abalone extract was frozen and dried at low temperature to remove water, obtaining meat dry powder.

[0045] (2) Take 10 g of the meat dry powder from step (1) and add 300 mL of water and mix evenly. Under the conditions of a 55 °C constant temperature water bath and a stirrer speed of 800 rpm, a non-specific enzyme with a mass concentration of 3% (based on the mass of the meat dry powder) was added for enzymatic hydrolysis for 4 h. During the enzymatic hydrolysis process, the pH value was adjusted to 6.5 - 7.5 with sodium hydroxide. After the enzymatic hydrolysis was completed, the enzymatic hydrolysis system was inactivated at 90 - 95 °C for 10 - 15 min. The inactivated system was centrifuged at a speed of 10000 rpm for 10 min, and the supernatant was taken as the crude extract. The crude extract was frozen and dried at low temperature to remove water, obtaining crude extract powder.

[0046] (3) Take 10 g of the crude extract powder from (2) and dissolve it in ultrapure water and make up the volume to 200 mL. Place it in a 37 °C constant temperature water bath and a stirrer speed of 800 rpm. While mixing, a mixed enzyme solution with a mass concentration of 1% (based on the mass of the crude extract powder) was added for a second enzymatic hydrolysis treatment for 3 h, obtaining a secondary enzymatic hydrolysis solution; in the mixed enzyme solution, the mass concentration of prolidase was 0.25%, the mass concentration of chymotrypsin was 0.5%, and the mass concentration of proteinase K was 0.25% (based on the mass of the crude extract powder).

[0047] (4) The secondary enzymatic hydrolysis solution in (3) was inactivated at 90 - 95 °C for 10 - 15 min, and then the system was centrifuged at a speed of 10000 rpm for 10 min. The supernatant was taken to obtain a polypeptide solution.

[0048] Example 2: Screening of polypeptides with high biological activity

[0049] (1) Filter the polypeptide solution obtained in Example 1 using an ultrafiltration tube with a molecular weight cut-off of 3 kDa, and collect the components with a molecular weight below 3 kDa.

[0050] (2) Further separate the components collected in step (1) using a Sephadex G-15 gel column (2.6×40 cm), elute with ultrapure water at a flow rate of 0.6 mL / min, collect the fractions of different absorption peaks at 280 nm, and measure the ACE inhibitory activity. The chromatogram and fraction collection are shown in Figure 2 , and the ACE inhibitory activities of different fractions are shown in Figure 3 . Fraction C has the highest ACE inhibitory activity, and fraction D has the highest polypeptide abundance.

[0051] (3) Use proteomics technology to analyze the fractions with advantages in step (2) (i.e., fraction C and fraction D) to obtain the amino acid sequences of all the contained polypeptides. Use PeptideRanker to score and rank the potential biological activities of the obtained polypeptide sequences, and screen the polypeptides with a score > 0.9 among them (as shown in Table 1), and a total of 9 polypeptides with amino acid sequences shown in SEQ ID NO.1-9 are obtained.

[0052] (4) Use the PeptideRanker tool to screen the polypeptides with an amino acid sequence score > 0.9 in step (3) for molecular docking prediction. The specific steps of molecular docking are as follows: Use the AutoDock Vina 1.1.2 software for molecular docking. The crystal structure of the human ACE-lisinopril complex (1O86) is from the RCSB Protein Data Bank (https: / / www.rcsb.org / ). The polypeptide molecules are constructed by PyMol 2.6 and energy minimization is performed. Use PyMol 2.6 to process the protein, remove water molecules and small molecule ligands, and add hydrogen, etc. Use AutoDock Tools to convert the receptor protein and peptide segments into the PDBQT format. Define the center of the docking box according to the position of the crystal ligand, and the side length of the box is Select the highest score of Vina docking as the final result and perform visual analysis in PyMol 2.6. After molecular docking, it is found that all 9 polypeptides can stably exist in the active pocket of angiotensin-converting enzyme, and the binding energy value is -5.8~-8.9 kcal / mol.

[0053] Chemically synthesize 9 polypeptides by solid-phase peptide synthesis method. After chemically synthesizing 9 polypeptides, measure their ACEi activity and antioxidant properties. The IC 50 value of ACEi is between 0.12 - 0.54 mg / mL, and the EC + of ABTS· 50was in the range of 0.12 mg / mL - 1.08 mg / mL. Among them, the peptide SSYPPLGRF had the best ACEi activity (IC 50 was 0.15 mg / mL), and the peptide PDRPW had the best antioxidant activity (EC 50 was 0.12 mg / mL). These 9 peptide sequences did not match in either BIOPEP-UWM or EROP-Moscow, indicating that all 9 polypeptides were novel sequences that had not been reported.

[0054] Table 1 Results of the bioactivity assay of the polypeptides obtained in Example 1

[0055]

[0056] Example 3

[0057] (1) After steaming abalone at 115 °C for 4.5 h, water was added and mixed evenly. After crushing with a pulverizer, an abalone extract was obtained; the abalone extract was frozen and dried at low temperature to remove moisture, obtaining a meat dry powder.

[0058] (2) Take 10 g of the meat dry powder from step (1) and add 300 mL of water and mix evenly. Under the conditions of a constant temperature water bath at 55 °C and a stirrer speed of 800 rpm, add a non-specific enzyme with a mass concentration of 3% (based on the mass of the meat dry powder) and carry out enzymatic hydrolysis for 4 h. During the enzymatic hydrolysis process, adjust the pH value to 6.5 - 7.5 with sodium hydroxide. After the enzymatic hydrolysis is completed, inactivate the enzyme in the hydrolyzed system at 90 - 95 °C for 10 - 15 min. Centrifuge the inactivated enzyme-treated system at a speed of 10000 rpm for 10 min, and take the supernatant as the crude extract. The crude extract was frozen and dried at low temperature to remove moisture, obtaining a crude extract powder.

[0059] (3) Take 10 g of the crude extract powder from (2) and dissolve it in ultrapure water and make up the volume to 200 mL. Place it in a constant temperature water bath at 37 °C and a stirrer speed of 800 rpm. While mixing, add a mixed enzyme solution with a mass concentration of 0.5% (based on the mass of the crude extract powder) and carry out a second enzymatic hydrolysis treatment for 3 h to obtain a secondary enzymatic hydrolysate; in the mixed enzyme solution, the mass concentration of prolyl endopeptidase is 0.125%, the mass concentration of chymotrypsin is 0.25%, and the mass concentration of proteinase K is 0.125% (based on the mass of the crude extract powder).

[0060] (4) Inactivate the secondary enzymatic hydrolysate from (3) at 90 - 95 °C for 10 - 15 min, then centrifuge the system at a speed of 10000 rpm for 10 min, and take the supernatant to obtain an abalone polypeptide solution.

[0061] Example 4

[0062] (1) After heating and steaming abalone at 115 °C for 4.5 h, add water and mix evenly. After crushing with a pulverizer, abalone extract is obtained; freeze the abalone extract and perform low-temperature drying to remove water to obtain meat dry powder.

[0063] (2) Take 10 g of the meat dry powder in step (1) and add 300 mL of water to mix evenly. Under the conditions of a constant water bath at 55 °C and a stirrer speed of 800 rpm, add a non-specific enzyme with a mass concentration of 3% (based on the mass of the meat dry powder) for enzymatic hydrolysis for 4 h. During the enzymatic hydrolysis process, adjust the pH value to 6.5 - 7.5 with sodium hydroxide. After the enzymatic hydrolysis is completed, heat the hydrolyzed system at 90 - 95 °C to inactivate the enzyme for 10 - 15 min. Centrifuge the enzyme-inactivated system at a speed of 10,000 rpm for 10 min, and take the supernatant as the crude extract. Freeze the crude extract and perform low-temperature drying to remove water to obtain the crude extract powder.

[0064] (3) Take 10 g of the crude extract powder in (2) and dissolve it in ultrapure water and make up the volume to 200 mL. Place it in a constant water bath at 37 °C and a stirrer speed of 800 rpm. While mixing, add a specific protease with a mass concentration of 3% (based on the mass of the crude abalone enzymatic hydrolysis product) for enzymatic hydrolysis treatment for 3 h to obtain a secondary enzymatic hydrolysis solution; in the mixed enzyme solution, the mass concentration of prolidase is 0.5%, the mass concentration of chymotrypsin is 1%, and the mass concentration of proteinase K is 0.5%.

[0065] (4) Heat the secondary enzymatic hydrolysis solution in (3) at 90 - 95 °C to inactivate the enzyme for 10 - 15 min, then centrifuge the system at a speed of 10,000 rpm for 10 min, and take the supernatant to obtain a polypeptide solution.

[0066] Example 5

[0067] (1) After heating and steaming abalone at 115 °C for 4.5 h, add water and mix evenly. After crushing with a pulverizer, abalone extract is obtained; freeze the abalone extract and perform low-temperature drying to remove water to obtain meat dry powder.

[0068] (2) Take 10 g of the meat dry powder in step (1) and add 300 mL of water to mix evenly. Under the conditions of a constant water bath at 55 °C and a stirrer speed of 800 rpm, add a non-specific enzyme with a mass concentration of 3% (based on the mass of the meat dry powder) for enzymatic hydrolysis for 4 h. During the enzymatic hydrolysis process, adjust the pH value to 6.5 - 7.5 with sodium hydroxide. After the enzymatic hydrolysis is completed, heat the hydrolyzed system at 90 - 95 °C to inactivate the enzyme for 10 - 15 min. Centrifuge the enzyme-inactivated system at a speed of 10,000 rpm for 10 min, and take the supernatant as the crude extract. Freeze the crude extract and perform low-temperature drying to remove water to obtain the crude extract powder.

[0069] (3) Take 10 g of the roughly extracted powder in (2), dissolve it in ultrapure water and make up the volume to 200 mL. Place it in a 37 °C constant temperature water bath and under the condition of a stirrer speed of 800 rpm. While mixing, add a mixed enzyme solution with a mass concentration of 1% (calculated based on the mass of the roughly extracted powder) for the second enzymatic hydrolysis treatment for 3 h to obtain a secondary enzymatic hydrolysate. In the mixed enzyme solution, the mass concentration of prolidase is 0.17%, the mass concentration of chymotrypsin is 0.33%, and the mass concentration of proteinase K is 0.5% (calculated based on the mass of the roughly extracted powder).

[0070] (4) Inactivate the enzyme in the secondary enzymatic hydrolysate in (3) at 90 - 95 °C for 10 - 15 min. Then centrifuge the system at a speed of 10000 rpm for 10 min, and take the supernatant to obtain a polypeptide solution.

[0071] Take 1 mg / mL of the polypeptide solutions obtained in Examples 1, 3 - 5 and Comparative Examples 1 - 2 respectively for ACEi activity determination. The results are shown in Table 2.

[0072] Table 2 ACEi activity determination of abalone polypeptide solutions in Examples 1 - 4 and Comparative Examples 1 - 2

[0073]

[0074] As can be seen from Table 2, the technical solution of the present invention significantly improves the ACEi activity of the abalone polypeptide solution, proving the feasibility of the preparation method of the present invention.

[0075] Comparative Example 1

[0076] (1) After steaming the abalone at 115 °C for 4.5 h, then add water and mix evenly. After crushing with a pulverizer, an abalone extract is obtained; the abalone extract is frozen and dried at low temperature to remove water to obtain a meat dry powder.

[0077] (2) Take 10 g of the meat dry powder in step (1) and add 300 mL of water and mix evenly. Under the conditions of a 55 °C constant temperature water bath and a stirrer speed of 800 rpm, add a non - specific enzyme with a mass concentration of 3% (calculated based on the mass of the meat dry powder) for enzymatic hydrolysis for 4 h. During the enzymatic hydrolysis process, adjust the pH value to 6.5 - 7.5 with sodium hydroxide. After the enzymatic hydrolysis is completed, inactivate the enzyme in the enzymatic hydrolysis system at 90 - 95 °C for 10 - 15 min. Centrifuge the inactivated enzyme treatment system at a speed of 10000 rpm for 10 min, and take the supernatant as the polypeptide solution.

[0078] Comparative Example 2

[0079] (1) After steaming the abalone at 115 °C for 4.5 h, then add water and mix evenly. After crushing with a pulverizer, an abalone extract is obtained; the abalone extract is frozen and dried at low temperature to remove water to obtain a meat dry powder.

[0080] (2) Take 10 g of the dried meat powder in (1), add 300 mL of water to mix evenly to obtain a mixture of abalone meat and water. Place it in a constant temperature water bath at 55 °C and stir it at a stirrer speed of 800 rpm. While mixing, add prolidase, chymotrypsin, and proteinase K with a mass concentration (calculated based on the mass of the dried meat powder) of 0.25%, 0.5%, and 0.25% respectively, and enzymatically hydrolyze for 3 h. During the enzymatic hydrolysis process, adjust the pH value to 6.5 - 7.5 with sodium hydroxide. After the enzymatic hydrolysis is completed, inactivate the enzymes at 90 - 95 °C for 10 - 15 min; then centrifuge the system at a speed of 10000 rpm for 10 min, and take the supernatant as the polypeptide solution.

[0081] Obviously, the above embodiments are only examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A polypeptide with high biological activity, characterized in that: The amino acid sequence of the polypeptide is shown in any one of SEQ ID NOs. 1-9.

2. The polypeptide according to claim 1, characterized in that The polypeptide is prepared by the following steps: S1, adding non-specific enzyme to the abalone extract to react and obtain a crude extract; S2. Adding a mixed enzyme containing prolyl endopeptidase, chymotrypsin and proteinase K to the crude extract to react and screen to obtain the polypeptide.

3. The polypeptide according to claim 2, characterized in that The abalone extract in step S1 is obtained by heating and crushing abalone, wherein the heating temperature is 110-130° C. and the heating time is 4-6 hours.

4. The polypeptide according to claim 2, characterized in that The reaction temperature in step S1 is 40°C-60°C, and the reaction pH is 6.5-7.

5.

5. The polypeptide according to claim 2, characterized in that In step S1, a non-specific enzyme is added to the abalone extract to react, and after the reaction, the enzyme is inactivated. After centrifugation, the supernatant is collected to obtain the crude extract, wherein the enzyme inactivation treatment is to heat the abalone extract after the reaction to 90-95° C. for 10-15 minutes.

6. The polypeptide according to claim 2, characterized in that The mass ratio of prolyl endopeptidase:chymotrypsin:proteinase K is (1-2):(1-2):(1-2).

7. The polypeptide according to claim 2, characterized in that The mass ratio of the mixed enzyme to the crude extract is (1-3):

100.

8. A gene encoding the polypeptide of claim 1.

9. Use of the polypeptide according to claim 1 in the preparation of a blood pressure lowering product.

10. Use of the polypeptide according to claim 1 in the preparation of antioxidant products.

Images