Active polypeptide and application thereof

Abstract

The invention provides an active polypeptide and application thereof, and belongs to the technical field of biological medicine. The amino acid sequence of the active polypeptide is G (KI) n, and n is more than or equal to 3 and less than or equal to 7; the active polypeptide can efficiently inhibit the growth of drug-resistant escherichia coli, acinetobacter baumannii and staphylococcus aureus, and has a good killing effect on gastric cancer cells HGC-27.

Description

Technical Field

[0001] This invention relates to the field of biomedical technology, and in particular to a class of active polypeptides and their applications. Background Technology

[0002] Antibiotics have long been used to treat infectious diseases caused by various pathogens. However, due to the overuse of antibiotics, drug-resistant bacteria are increasing, making the development of novel antibacterial drugs to replace antibiotics an urgent priority. Against this backdrop, antimicrobial peptides have attracted widespread attention due to their unique antibacterial mechanism that makes them less likely to induce bacterial resistance.

[0003] Most antimicrobial peptides are amphiphilic cationic peptides. Their positive charge allows them to interact electrostatically with the negatively charged bacterial cell membrane, promoting adsorption and accumulation on the bacterial cell membrane surface. When a certain concentration is reached, the antimicrobial peptides affect the bacterial cell membrane, thereby exerting an antibacterial effect. Antimicrobial peptides are a key component of the innate immune system and are small molecule peptides widely found in various organisms in nature. They exhibit broad inhibitory effects against viruses, drug-resistant bacteria, fungi, parasites, and cancer cells, making them a promising candidate for applications in the pharmaceutical and food additive industries.

[0004] In addition, peptide drugs have the characteristics of low toxicity, targeted and specific modification, and small molecular weight, thus becoming a key area of ​​research and development for novel antibacterial and antitumor drugs in recent years. Summary of the Invention

[0005] The purpose of this invention is to provide a class of active polypeptides and their applications, wherein the active polypeptides can effectively inhibit the growth of drug-resistant Escherichia coli, Acinetobacter baumannii and Staphylococcus aureus, and have a good killing effect on gastric cancer cells HGC-27.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a class of active polypeptides, wherein the amino acid sequence of the active polypeptide is G(KI)n, 3≤n≤7, and n is an integer.

[0007] Preferably, the active polypeptide has an acetylated amino terminus and an amino-modified carboxyl terminus.

[0008] Preferably, the active polypeptide is made of L-type amino acids and / or D-type amino acids.

[0009] More preferably, the L-type amino acid and / or D-type amino acid includes one or more of isoleucine, lysine, and glycine.

[0010] The present invention also provides the application of the aforementioned active polypeptide in the preparation of antibacterial agents.

[0011] Preferably, the antibacterial agent has the effect of inhibiting drug-resistant Escherichia coli, Staphylococcus aureus and Acinetobacter baumannii.

[0012] The present invention also provides the use of the described active polypeptide in the preparation of drugs for antibacterial infection.

[0013] Preferably, the drug can inhibit the growth of drug-resistant Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii.

[0014] The present invention also provides the application of the aforementioned active polypeptide in inhibiting bacteria.

[0015] The present invention also provides the application of the aforementioned active polypeptide in the preparation of antitumor drugs.

[0016] The beneficial effects of this invention compared to the prior art are as follows: The active polypeptide provided by this invention can effectively inhibit the growth of drug-resistant Escherichia coli, Acinetobacter baumannii and Staphylococcus aureus, and has a good killing effect on gastric cancer cells HGC-27, showing good application prospects.

[0017] In addition to their excellent antibacterial and anti-biofilm effects, the active polypeptides provided by this invention also have potential anti-tumor activity and anti-tumor application value. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The high-performance liquid chromatogram of the active peptide prepared in Example 1; Figure 2 The high-performance liquid chromatogram of the active peptide prepared in Example 2; Figure 3 The high-performance liquid chromatogram of the active peptide prepared in Example 3; Figure 4 The high-performance liquid chromatogram of the active peptide prepared in Example 4; Figure 5 The high-performance liquid chromatogram of the active peptide prepared in Example 5; Figure 6 The mass spectrum of the active polypeptide prepared in Example 1; Figure 7 The mass spectrum of the active polypeptide prepared in Example 2; Figure 8 The mass spectrum of the active polypeptide prepared in Example 3; Figure 9 The mass spectrum of the active polypeptide prepared in Example 4; Figure 10 The mass spectrum of the active polypeptide prepared in Example 5; Figure 11 The results of the inhibitory effects of the active peptides prepared in Examples 1-5 on drug-resistant Escherichia coli are as follows. Figure 12 The results of the active peptides prepared in Examples 1-5 against drug-resistant Staphylococcus aureus are shown. Figure 13 The results of the active peptides prepared in Examples 1-5 against drug-resistant Acinetobacter baumannii are shown. Figure 14 The results are from flow cytometry analysis of drug-resistant Escherichia coli. Figure 15 The results are from flow cytometry analysis of drug-resistant Staphylococcus aureus. Figure 16 The results are from flow cytometry analysis of drug-resistant Acinetobacter baumannii. Figure 17 The result of the ablation of the biofilm; Figure 18 The results are from the hemolysis experiment of the polypeptide; Figure 19 The results are from the 293T cell toxicity assay. Figure 20 These are the results of the HGC cytotoxicity experiment. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0021] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0023] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] This invention provides a class of active polypeptides, wherein the amino acid sequence of the active polypeptide is G(KI)n, 3≤n≤7, and n is an integer.

[0026] In this invention, the active polypeptide preferably has an acetylated amino terminus and an amino-modified carboxyl terminus; the active polypeptide is preferably made of L-type amino acids and / or D-type amino acids; the L-type amino acids and / or D-type amino acids preferably include one or more of isoleucine, lysine, and glycine; when the active polypeptide is prepared with isoleucine, lysine, and glycine, n=3, and its amino acid sequence is GKIKIKI (SEQ ID No. 1); when the active polypeptide is prepared with isoleucine, lysine, and glycine, n=4, and its amino acid sequence is GKIKIKIKI (SEQ ID No. 2); when the active polypeptide is prepared with isoleucine, lysine, and glycine, n=5, and its amino acid sequence is GKIKIKIKIKI (SEQ ID No. 3); when the active polypeptide is prepared with isoleucine, lysine, and glycine, n=6, and its amino acid sequence is GKIKIKIKIKIKI (SEQ ID No. 3). No. 4); When the active polypeptide is prepared with isoleucine, lysine and glycine, n=7, and its amino acid sequence is GKIKIKIKIKIKIKI (SEQ ID No. 5).

[0027] The present invention also provides the application of the aforementioned active polypeptide in the preparation of antibacterial agents.

[0028] In this invention, the antibacterial agent has the effect of inhibiting drug-resistant Escherichia coli, Staphylococcus aureus and Acinetobacter baumannii.

[0029] The present invention also provides the use of the described active polypeptide in the preparation of drugs for antibacterial infection.

[0030] In this invention, the drug can inhibit the growth of drug-resistant Escherichia coli, Staphylococcus aureus and Acinetobacter baumannii; the drug preferably also includes diluents, excipients, fillers, binders, humectants, disintegrants, absorption promoters, adsorbents, surfactants or lubricants.

[0031] The present invention also provides the application of the aforementioned active polypeptide in inhibiting bacteria.

[0032] The present invention also provides the application of the aforementioned active polypeptide in the preparation of antitumor drugs.

[0033] Example 1 A method for preparing an active polypeptide Ac-GKIKIKI-NH2, comprising the following steps: (1) At 20℃, 1g of Rink Amide MBHA resin was soaked in 15ml of DCM (dichloromethane) for 3h. After the resin was fully swollen, the DCM (dichloromethane) was dried, and the resin was washed three times with 20mL of DMF (N,N-dimethylformamide) and methanol. 20ml of 25% piperidine solution (DMF:piperidine = 3:1) was added to remove the Fmoc protecting group. The resin was then dried, and the above piperidine solution was added again and reacted for 5min. The resin was then dried again to remove the protection of the swollen Rink Amide MBHA resin. The resin was then dried and washed three times with 20mL of DMF (N,N-dimethylformamide) and methanol. The resin was then washed with DMF (N,N-dimethylformamide) to remove the residual deprotecting agent. (2) The washed Rink Amide MBHA resin was soaked in 15 ml DMF solvent with 0.25 g Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), and 0.5 ml DIEA (N,N-diisopropylethylamine), 0.2 g HoBt (1-hydroxybenzotriazole), and 0.49 g TBTU (2-(1H-benzotriazo-L-1-yl)-1,1,3,3-tetramethylurea tetrafluoroborate) was added. The mixture was reacted at 20 °C for 2 h, washed three times with DMF and methanol, and 10 mg of the resin was taken for ninhydrin detection. (3) Add 15 ml DMF, 7.5 ml acetic anhydride and 7.5 ml pyridine to the reaction system, cap the reaction at 20 °C for 60 min, wash with DMF and methanol until the reaction system is colorless when tested with ninhydrin; add 20 ml of 25% piperidine solution (DMF:piperidine = 3:1), deprotect at 20 °C for 30 min, wash until the reaction system is blue when tested with ninhydrin; (4) Add 0.7g Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), 0.5ml DIEA (N,N-diisopropylethylamine), 0.2g HoBt (1-hydroxybenzotriazole), and 0.49g TBTU (2-(1H-benzotriazo-L-1-yl)-1,1,3,3-tetramethylurea tetrafluoroborate) to the reaction system, immerse in DMF solution, react at 20°C for 2h, wash, until the reaction system is colorless according to ninhydrin test; add 20ml of 25% piperidine solution (DMF:piperidine = 3:1), remove the Fmoc protecting group, dry under vacuum, add the above piperidine solution again, react for 5min, dry under vacuum again, perform deprotection, wash, until the reaction system is blue according to ninhydrin test; (5) Repeat step (4) and add Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), and Fmoc-Gly(Otbu)-OH (fluorenylmethoxycarbonyl-glycine-4-tert-butyl ester) to the reaction system in the following amounts: 0.5g Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), 0.7g Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), and 0.4g Fmoc-Gly(Otbu)-OH (fluorenylmethoxycarbonyl-glycine-4-tert-butyl ester). The reaction was carried out at 20°C for 2 hours. After all amino acid sequences were attached, 20 ml of 25% piperidine solution (DMF:piperidine = 3:1) was added to remove the Fmoc protecting group. The mixture was then dried. The piperidine solution was added again and reacted for 5 minutes. The mixture was then dried again and deprotected. The reaction was carried out at 20°C for 30 minutes to remove the Fmoc protecting group at the end of the polypeptide chain. 7.5 ml of acetic anhydride and 7.5 ml of pyridine were added to the reaction system. After treatment, the mixture was washed with DMF and methanol in sequence and then dried. (6) Wash thoroughly with 15 ml of methanol, and dry until the resin is granular. Add cutting solution B (composed of TFA (trifluoroacetic acid), water, EDT (ethylene dithiol), and TMSBr (trimethylbromosilane) in a volume ratio of 95:2:2:1), and cut at 20°C for 2.5 h. Transfer the cutting solution containing the resin to a new reaction tube, filter under reduced pressure, and collect the filtrate. Add the collected filtrate dropwise to 2-3 times the volume of pre-cooled peptide precipitation reagent: anhydrous diethyl ether: petroleum ether = 2:1 (V / V), mix thoroughly (a milky white precipitate will be visible at this point), and centrifuge at 4000 rpm for 10 min. Wash 2-3 times with the precipitation reagent and dry in a vacuum freeze dryer for 12 h to obtain the synthesized crude peptide product. Purify by high performance liquid chromatography to obtain the active peptide Ac-GKIKIKI-NH2.

[0034] Example 2 A method for preparing an active polypeptide Ac-GKIKIKIKI-NH2, comprising the following steps: (1) At 20℃, 1g of Rink Amide MBHA resin was soaked in 15ml of DCM (dichloromethane) for 3h. After the resin was fully swollen, the DCM (dichloromethane) was dried, and the resin was washed three times with 20mL of DMF (N,N-dimethylformamide) and methanol. 20ml of 25% piperidine solution (DMF:piperidine = 3:1) was added to remove the Fmoc protecting group. The resin was then dried, and the above piperidine solution was added again and reacted for 5min. The resin was then dried again to remove the protection of the swollen Rink Amide MBHA resin. The resin was then dried and washed three times with 20mL of DMF (N,N-dimethylformamide) and methanol. The resin was then washed with DMF (N,N-dimethylformamide) to remove the residual deprotecting agent. (2) The washed Rink Amide MBHA resin was soaked in 15 ml DMF solvent with 0.25 g Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), and 0.5 ml DIEA (N,N-diisopropylethylamine), 0.2 g HoBt (1-hydroxybenzotriazole), and 0.49 g TBTU (2-(1H-benzotriazo-L-1-yl)-1,1,3,3-tetramethylurea tetrafluoroborate) was added. The mixture was reacted at 20 °C for 2 h, washed three times with DMF and methanol, and 10 mg of the resin was taken for ninhydrin detection. (3) Add 15 ml DMF, 7.5 ml acetic anhydride and 7.5 ml pyridine to the reaction system, cap at 20 °C for 60 min, wash with DMF and methanol until the reaction system is colorless according to ninhydrin test; add 20 ml of 25% piperidine solution (DMF:piperidine = 3:1), deprotect at 20 °C for 30 min, wash until the reaction system is blue according to ninhydrin test; (4) Add 0.7g Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), 0.5ml DIEA (N,N-diisopropylethylamine), 0.2g HoBt (1-hydroxybenzotriazole), and 0.49g TBTU (2-(1H-benzotriazo-L-1-yl)-1,1,3,3-tetramethylurea tetrafluoroborate) to the reaction system, immerse in DMF solution, react at 20°C for 2h, wash, until the reaction system is colorless according to ninhydrin test; add 20 ml of 25% piperidine solution (DMF:piperidine = 3:1), remove the Fmoc protecting group, dry under vacuum, add the above piperidine solution again, react for 5 min, dry under vacuum again, perform deprotection, wash, until the reaction system is blue according to ninhydrin test; (5) Repeat step (4) and add Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), and Fmoc-Gly(Otbu)-OH (fluorenylmethoxycarbonyl-glycine-4-tert-butyl ester) to the reaction system in the following order according to the amino acid sequence of IKIKIKIKG: 0.5g Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), 0.7g Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), and 0.4g Fmoc-Gly(Otbu)-OH (fluorenylmethoxycarbonyl-glycine-4-tert-butyl ester). The reaction was carried out at 20°C for 2 hours. After all amino acid sequences were attached, 20 ml of 25% piperidine solution (DMF:piperidine = 3:1) was added to remove the Fmoc protecting group. The mixture was then dried under vacuum. The piperidine solution was added again and reacted for 5 minutes. The mixture was then dried under vacuum again for deprotection. The reaction was carried out at 20°C for 30 minutes to remove the Fmoc protecting group at the end of the polypeptide chain. 7.5 ml of acetic anhydride and 7.5 ml of pyridine were added to the reaction system. After treatment, the mixture was washed with DMF and methanol in sequence and then dried under vacuum. (6) Wash thoroughly with 15 ml of methanol, and dry until the resin is granular. Add cutting solution B (composed of TFA (trifluoroacetic acid), water, EDT (ethylene dithiol), and TMSBr (trimethylbromosilane) in a volume ratio of 95:2:2:1), and cut at 20°C for 2.5 h. Transfer the cutting solution containing the resin to a new reaction tube, filter under reduced pressure, and collect the filtrate. Add the collected filtrate dropwise to 2-3 times the volume of pre-cooled peptide precipitation reagent: anhydrous diethyl ether: petroleum ether = 2:1 (V / V), mix thoroughly (a milky white precipitate will be visible at this point), and centrifuge at 9000 rpm for 5 min. Wash 2-3 times with the precipitation reagent and dry in a vacuum freeze dryer for 12 h to obtain the synthesized crude peptide product. Purify by high performance liquid chromatography to obtain the active peptide Ac-GKIKIKIKI-NH2.

[0035] Example 3 A method for preparing an active polypeptide Ac-GKIKIKIKIKI-NH2, comprising the following steps: (1) At 25°C, 1g of Rink Amide MBHA resin was soaked in 20mL of DCM (dichloromethane) for 2h. After the resin was fully swollen, the DCM (dichloromethane) was dried. The resin was washed three times with 20mL of DMF (N,N-dimethylformamide) and methanol. After the Rink Amide MBHA resin was deprotected, it was dried. The resin was washed three times with 20mL of DMF (N,N-dimethylformamide) and methanol. The resin was then washed with DMF (N,N-dimethylformamide) to remove the residual deprotection reagent. (2) The washed Rink Amide MBHA resin was soaked in 20 mL of DMF solvent with 0.3 g Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), 0.6 mL DIEA (N,N-diisopropylethylamine), 0.25 g HoBt (1-hydroxybenzotriazole), and 0.55 g TBTU (2-(1H-benzotriazo-L-1-yl)-1,1,3,3-tetramethylurea tetrafluoroborate). The reaction was carried out at 25 °C for 1.5 h. The resin was washed three times with DMF and methanol. 10 mg of the resin was taken for ninhydrin detection. (3) Add 20 ml DMF, 10 ml acetic anhydride and 10 ml pyridine to the reaction system, cap the reaction system at 25 °C for 30 min, wash with DMF and methanol until the reaction system is colorless when tested with ninhydrin; add piperidine solution, deprotect at 25 °C for 15 min, wash until the reaction system is blue when tested with ninhydrin; (4) Add 0.75g Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), 0.6ml DIEA (N,N-diisopropylethylamine), 0.25g HoBt (1-hydroxybenzotriazole), and 0.49g TBTU (2-(1H-benzotriazo-L-1-yl)-1,1,3,3-tetramethylurea tetrafluoroborate) to the reaction system, immerse in DMF solution, react at 25°C for 1h, wash until the reaction system is colorless according to ninhydrin test; add piperidine for deprotection, wash until the reaction system is blue according to ninhydrin test; (5) Repeat step (4), and add 0.55g Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), 0.75g Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), and 0.5g Fmoc-Gly(Otbu)-OH (fluorenylmethoxycarbonyl-glycine-4-tert-butyl ester) to the reaction system in sequence according to the amino acid sequence of IKIKIKIKIKG. ​​Contact the reaction at 25℃ for 1h. After all the amino acid sequences are attached, add piperidine and react at 25℃ for 15min to remove the Fmoc protecting group at the end of the polypeptide chain. Add 10ml acetic anhydride and 10ml pyridine to the reaction system. After treatment, wash with DMF and methanol in sequence and then dry. (6) Wash thoroughly with 20 ml of methanol, dry until the resin is granular, add cutting solution B (composed of TFA (trifluoroacetic acid), water, EDT (ethylene dithiol) and TMSBr (trimethylbromosilane) in a volume ratio of 95:2:2:1), cut at 25°C for 2 h, precipitate, purify, and obtain the active polypeptide Ac-GKIKIKIKIKI-NH2.

[0036] Example 4 A method for preparing an active polypeptide Ac-GKIKIKIKIKIKI-NH2, comprising the following steps: (1) At 20℃, 1g of Rink Amide MBHA resin was soaked in 15ml of DCM (dichloromethane) for 3h. After the resin was fully swollen, the DCM (dichloromethane) was dried, and the resin was washed three times with 20mL of DMF (N,N-dimethylformamide) and methanol. 20ml of 25% piperidine solution (DMF:piperidine = 3:1) was added to remove the Fmoc protecting group. The resin was then dried, and the above piperidine solution was added again and reacted for 5min. The resin was then dried again to remove the protection of the swollen Rink Amide MBHA resin. The resin was then dried and washed three times with 20mL of DMF (N,N-dimethylformamide) and methanol. The resin was then washed with DMF (N,N-dimethylformamide) to remove the residual deprotecting agent. (2) The washed Rink Amide MBHA resin was soaked in 15 ml DMF solvent with 0.25 g Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), and 0.5 ml DIEA (N,N-diisopropylethylamine), 0.2 g HoBt (1-hydroxybenzotriazole), and 0.49 g TBTU (2-(1H-benzotriazo-L-1-yl)-1,1,3,3-tetramethylurea tetrafluoroborate) was added. The mixture was reacted at 20 °C for 2 h, washed three times with DMF and methanol, and 10 mg of the resin was taken for ninhydrin detection. (3) Add 15 ml DMF, 7.5 ml acetic anhydride and 7.5 ml pyridine to the reaction system, cap at 20 °C for 60 min, wash with DMF and methanol until the reaction system is colorless according to ninhydrin test; add 20 ml of 25% piperidine solution (DMF:piperidine = 3:1), deprotect at 20 °C for 30 min, wash until the reaction system is blue according to ninhydrin test; (4) Add 0.7g Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), 0.5ml DIEA (N,N-diisopropylethylamine), 0.2g HoBt (1-hydroxybenzotriazole), and 0.49g TBTU (2-(1H-benzotriazo-L-1-yl)-1,1,3,3-tetramethylurea tetrafluoroborate) to the reaction system, immerse in DMF solution, react at 20°C for 2h, wash, until the reaction system is colorless according to ninhydrin test; add 20 ml of 25% piperidine solution (DMF:piperidine = 3:1), remove the Fmoc protecting group, dry under vacuum, add the above piperidine solution again, react for 5 min, dry under vacuum again, perform deprotection, wash, until the reaction system is blue according to ninhydrin test; (5) Repeat step (4) and add Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), and Fmoc-Gly(Otbu)-OH (fluorenylmethoxycarbonyl-glycine-4-tert-butyl ester) to the reaction system in the following order of amino acid sequence: 0.5g Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), 0.7g Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), and 0.4g Fmoc-Gly(Otbu)-OH (fluorenylmethoxycarbonyl-glycine-4-tert-butyl ester). The reaction was carried out at 20°C for 2 hours. After all amino acid sequences were attached, 20 ml of 25% piperidine solution (DMF:piperidine = 3:1) was added to remove the Fmoc protecting group. The mixture was then dried under vacuum. The piperidine solution was added again and reacted for 5 minutes. The mixture was then dried under vacuum again for deprotection. The reaction was carried out at 20°C for 30 minutes to remove the Fmoc protecting group at the end of the polypeptide chain. 7.5 ml of acetic anhydride and 7.5 ml of pyridine were added to the reaction system. After treatment, the mixture was washed with DMF and methanol in sequence and then dried under vacuum. (6) Wash thoroughly with 15 ml of methanol, and dry until the resin is granular. Add cutting solution B (composed of TFA (trifluoroacetic acid), water, EDT (ethylene dithiol), and TMSBr (trimethylbromosilane) in a volume ratio of 95:2:2:1), and cut at 20°C for 2.5 h. Transfer the cutting solution containing the resin to a new reaction tube, filter under reduced pressure, and collect the filtrate. Add the collected filtrate dropwise to 2-3 times the volume of pre-cooled peptide precipitation reagent: anhydrous diethyl ether: petroleum ether = 2:1 (V / V), mix thoroughly (a milky white precipitate will be visible at this point), and centrifuge at 4000-9000 rpm for 5-10 min. Wash 2-3 times with the precipitation reagent and dry in a vacuum freeze dryer for 12 h to obtain the synthesized crude peptide product. Purify by high performance liquid chromatography to obtain the active peptide Ac-GKIKIKIKIKIKI-NH2.

[0037] Example 5 A method for preparing an active polypeptide Ac-GKIKIKIKIKIKIKI-NH2, comprising the following steps: (1) At 23°C, 1g of Rink Amide MBHA resin was soaked in 18ml of DCM (dichloromethane) for 2.5h. After the resin was fully swollen, the DCM (dichloromethane) was dried out. The resin was washed three times with 20mL of DMF (N,N-dimethylformamide) and methanol. After the Rink Amide MBHA resin was deprotected, it was dried out. The resin was washed three times with 20mL of DMF (N,N-dimethylformamide) and methanol. The resin was then washed with DMF (N,N-dimethylformamide) to remove the residual deprotection reagent. (2) The washed Rink Amide MBHA resin was soaked in 18 ml DMF solvent with 0.28 g Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), and 0.58 ml DIEA (N,N-diisopropylethylamine), 0.24 g HoBt (1-hydroxybenzotriazole), and 0.52 g TBTU (2-(1H-benzotriazo-L-1-yl)-1,1,3,3-tetramethylurea tetrafluoroborate) was added. The reaction was carried out at 23 °C for 1.8 h. The resin was washed three times with DMF and methanol. 10 mg of the resin was taken for ninhydrin detection. (3) Add 18 ml DMF, 8 ml acetic anhydride and 8 ml pyridine to the reaction system, cap the reaction at 23°C for 40 min, wash with DMF and methanol until the reaction system is colorless when tested with ninhydrin; add piperidine solution, deprotect at 23°C for 20 min, wash until the reaction system is blue when tested with ninhydrin; (4) Add 0.72g Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), 0.55ml DIEA (N,N-diisopropylethylamine), 0.24g HoBt (1-hydroxybenzotriazole), and 0.49g TBTU (2-(1H-benzotriazo-L-1-yl)-1,1,3,3-tetramethylurea tetrafluoroborate) to the reaction system, immerse in DMF solution, and react at 23°C for 1.5h. Wash until the reaction system is colorless according to ninhydrin test; add piperidine for deprotection, wash until the reaction system is blue according to ninhydrin test; (5) Repeat step (4), and add 0.52g Fmoc-Ile(Otbu)-OH (fluorenylmethoxycarbonyl-isoleucine-4-tert-butyl ester), 0.72g Fmoc-Lys(Otbu)-OH (fluorenylmethoxycarbonyl-lysine-4-tert-butyl ester), and 0.45g Fmoc-Gly(Otbu)-OH (fluorenylmethoxycarbonyl-glycine-4-tert-butyl ester) to the reaction system in sequence according to the amino acid sequence of IKIKIKIKIKIKIKG. ​​Contact reaction at 23℃ for 1.5h. After all amino acid sequences are attached, add piperidine and react at 23℃ for 20min to remove the Fmoc protecting group at the end of the polypeptide chain. Add 8ml acetic anhydride and 8ml pyridine to the reaction system. After treatment, wash with DMF and methanol in sequence and dry under vacuum. (6) Wash thoroughly with 18 ml of methanol, dry until the resin is granular, add cutting solution B (composed of TFA (trifluoroacetic acid), water, EDT (ethylene dithiol) and TMSBr (trimethylbromosilane) in a volume ratio of 95:2:2:1), cut at 23°C for 2.2 h, precipitate, purify, and obtain the active polypeptide Ac-GKIKIKIKIKIKIKI-NH2.

[0038] Experimental Example 1 The purity of the active peptides prepared in Examples 1-5 was determined using Shimadzu high-performance liquid chromatography (HPLC): 0.01 g of the active peptide was dissolved in 0.5 ml of aqueous solution and filtered through a 0.22 μm organic filter membrane for later use. The mobile phase was a gradient mixture of acetonitrile and ultrapure water containing 1‰ TFA (trifluoroacetic acid). The stationary phase was a C18 reverse-phase column, and the flow rate was 1 ml / min. After column equilibration using gradient elution, 20 μl of sample was loaded. The acetonitrile gradient was set to continuously change from 5% to 100% over 45 min. The results are as follows: Figures 1 to 5 As shown.

[0039] The results showed that the retention times of the active peptides prepared in Examples 1-5 in the C18 column were 16.62 min (n=3), 19.03 min (n=4), 18.56 min (n=5), 18.98 min (n=6), and 18.98 min (n=7), respectively. In HPLC, they were a single elution peak with high purity, which met the requirements of subsequent experiments.

[0040] Experimental Example 2 The molecular weight of the active peptides prepared in Examples 1-5 was determined by mass spectrometry: 0.01 g of the active peptide was dissolved in 0.5 ml of aqueous solution, diluted 100 times, and filtered through a 0.22 μm organic filter membrane. Mass spectrometry analysis was performed using a liquid chromatography-mass spectrometry (LC-MS) mass spectrometer. The column was a Shim-pack XR-ODS11 75 mm × 2.0 mm L.D., 2.2 μm; the mobile phase was methanol / water; the mass spectrometer settings were: ESI source, positive ion mode, DL temperature 250 °C, Heat Block temperature 400 °C, nebulizer flow rate 1.5 L / min, dryer flow rate 10 L / min, ion source voltage +4.5 kV, and detector voltage 1.2 kV. The results are as follows: Figures 6 to 10 As shown.

[0041] The results showed that the theoretical molecular weight of the active polypeptide obtained in Example 1 was 840.11, and mass spectrometry analysis showed that the mass-to-charge ratio of its fragment ion peaks [M+H] was... + [M+2H] 2+ [M+3H] 3+ [M+4H] 4+ The results of mass spectrometry analysis (841.15, 421.05, 281.05, 211.05) indicate that the peptide synthesis was successful. The theoretical molecular weight of the active peptide obtained in Example 2 is 1081.47. Mass spectrometry analysis shows that the mass-to-charge ratio of its fragment ion peaks [M+H] is... + [M+2H] 2+ [M+3H] 3+ [M+4H] 4+ The results of mass spectrometry analysis (1082.45, 541.75, 361.50, 271.35) indicate that the peptide synthesis was successful. The theoretical molecular weight of the active peptide obtained in Example 3 is 1322.81. Mass spectrometry analysis shows that the mass-to-charge ratio of its fragment ion peaks [M+H] is... + [M+2H] 2+ [M+3H] 3+ [M+4H] 4+ The mass spectrometry results (1323.81, 662.40, 441.94, 331.70) correspond to the successful synthesis of the polypeptide. The theoretical molecular weight of the active polypeptide obtained in Example 4 is 1564.15. Mass spectrometry analysis shows that the mass-to-charge ratio of its fragment ion peaks [M+H] is... + [M+2H] 2+ [M+3H] 3+ [M+4H] 4+The mass spectrometry results (1565.15, 783.10, 522.40, 392.05) correspond to the successful synthesis of the polypeptide. The theoretical molecular weight of the active polypeptide prepared in Example 5 is 1805.50. Mass spectrometry analysis shows that the mass-to-charge ratio of its fragment ion peaks [M+H] is... + [M+2H] 2+ [M+3H] 3+ [M+4H] 4+ The results of mass spectrometry detection (1806.50, 903.75, 602.85, 452.35) indicate that the active peptide was successfully synthesized.

[0042] Experimental Example 3 The antibacterial properties of the active peptides prepared in Examples 1-5 against drug-resistant Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii were determined.

[0043] Five bioactive peptides were tested for their effectiveness against drug-resistant Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii (drug-resistant Escherichia coli is described in Antibiotic resistance genes in...). Escherichia coli – literature review. Critical Reviews in Microbiology , 1–35.), drug-resistant Staphylococcus aureus (described in Molecular Mechanisms of Drug Resistance in Staphylococcus aureus . Int. J. Mol. Sci. 2022, 23 , 8088.) and drug-resistant Acinetobacter baumannii (described in Acinetobacter baumannii Antibiotic Resistance Mechanisms. Pathogens 2021, 10 The antibacterial properties of the sample (373.) stored at Anhui University of Technology (Wuhu, China) are as follows: The specific steps are as follows: The bacteria were cultured in LB medium at 37°C until they reached the logarithmic growth phase (bacterial concentration of OD). 600=0.6~0.8), take 500μl of bacterial culture from the cultured test tube and put it into 50mL of fresh sterile LB liquid medium (0.5g peptone, 0.25g yeast extract, 0.5g sodium chloride, 1g agar powder to prepare 50mL LB liquid medium), and incubate at 225rpm and 37℃ for 4h to obtain a bacterial culture with a concentration between 0.6 and 0.8 (at this time the bacteria are in the logarithmic growth phase and the bacterial cells are in the best condition). Under aseptic conditions, a series of active peptide solutions with concentration gradients of 2× were prepared according to the following formulas: (16, 32, 64, 128 μg / mL for n=3 active peptide amino acid sequences; 4, 8, 16, 32 μg / mL for n=4 active peptide amino acid sequences; 0.25, 0.5, 1, 2 μg / mL for n=5 active peptide amino acid sequences; 0.125, 0.25, 0.5, 1 μg / mL for n=6 active peptide amino acid sequences; and 0.0625, 0.125, 0.25, 0.5 μg / mL for n=7 active peptide amino acid sequences). 200 μl of bacterial culture (OD) was added to each solution. 600 =0.5), mix thoroughly, and let stand for 30 min. Take 50 μl of the statically incubated bacterial solution, spread it on a plate, and incubate at 37℃ upright for 0.5 h. Then, invert the plate and incubate overnight. Take photos. The results are as follows. Figures 11 to 13 As shown.

[0044] The results showed that the active peptides had good antibacterial effects against drug-resistant Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii. For drug-resistant Escherichia coli, the inhibition rates were all above 98% when the concentrations of G(KI)n (n=3) were 128 μg / mL, G(KI)n (n=4) were 16 μg / mL, G(KI)n (n=5) were 1 μg / mL, G(KI)n (n=6) were 0.25 μg / mL, and G(KI)n (n=7) were 0.125 μg / mL. Against drug-resistant Staphylococcus aureus, the inhibition rates were also above 98% when the concentrations of G(KI)n (n=3) were 128 μg / mL, G(KI)n (n=4) were 32 μg / mL, and G(KI)n (n=5) were 4 μg / mL. When the concentration of G(KI)n (n=6) was 0.25 μg / mL, and the concentration of G(KI)n (n=7) was 0.125 μg / mL, the inhibition rate reached over 99%. Against drug-resistant Acinetobacter baumannii, the inhibition rate reached over 99% when the concentration of G(KI)n (n=3) was 128 μg / mL, the concentration of G(KI)n (n=4) was 4 μg / mL, the concentration of G(KI)n (n=5) was 0.25 μg / mL, the concentration of G(KI)n (n=6) was 0.125 μg / mL, and the concentration of G(KI)n (n=7) was 0.0625 μg / mL.

[0045] Test Example 4 The MICs of the active peptides prepared in Example 2 against drug-resistant Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii (drug-resistant Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii were stored at Anhui University of Technology (Wuhu, China)) were determined and compared with the MICs of previously reported peptides. The results are shown in Table 1.

[0046] Table 1. Results of the determination of minimum inhibitory concentration (MIC) values.

[0047] For MRSA, the MIC of G(KI)n (n=5) in this invention is 4 μg / mL, which is much lower than that of Pexiganan (50 μg / mL) and DP7 (7.5 μg / mL), indicating that it can effectively inhibit the growth of MRSA at lower concentrations. For MDR E. coliThe MIC of G(KI)n (n=5) in this invention is 4 μg / mL, significantly lower than that of LL-37 (36 μg / mL), Bac8c (16 μg / mL), and Cecropin A-melittin hybrid peptide (10 μg / mL). Its potency is 9 times that of LL-37, 4 times that of Bac8c, and 2.5 times that of Cecropin A-melittin hybrid peptide. For MDR... A. baumannii The most prominent advantage of G(KI)n (n=5) in this invention is its MIC as low as 0.25 μg / mL, which is much lower than WLBU2 (4 μg / mL) and Esc(1-21) (8 μg / mL). Its potency is 16 times that of WLBU2 and 32 times that of Esc(1-21), respectively. This is the lowest MIC value among all active peptides in the table.

[0048] The G(KI)n (n=5) in this invention is effective against three important clinically important multidrug-resistant bacteria (MRSA, MDR). E. coli MDR A. baumannii It exhibits strong activity (low MIC). For MDR A. baumannii Exhibiting superior activity, the MIC value of 0.25 μg / mL indicates that G(KI)n (n=5) in this invention is effective for clinically challenging MDR conditions that often lack effective treatment options. A. baumannii It has extremely high potential effectiveness.

[0049] Experimental Example 5 The active peptides prepared in Examples 1-5 were analyzed by flow cytometry.

[0050] First, the bacteria (drug-resistant Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii, stored at Anhui University of Technology (Wuhu, China)) were cultured in LB medium at 37°C until they reached the logarithmic growth phase (bacterial concentration of OD). 600=0.6~0.8), take 500μl of bacterial culture from the culture tube and put it into 50ml of fresh sterile LB liquid medium, incubate at 225rpm and 37℃ for 4h to obtain a bacterial culture with a concentration between 0.6 and 0.8 (at this time the bacteria are in the logarithmic growth phase and the bacterial cells are in the best state). Under aseptic conditions, prepare a series of active peptide solutions with concentration gradients of 2× according to the following formula: (when the active peptide amino acid sequence n=3, prepare gradient concentrations of 16, 32, 64, 128 μg / mL; when the active peptide amino acid sequence n=4, prepare gradient concentrations of 4, 8, 16, 32 μg / mL; when the active peptide amino acid sequence n=5, prepare gradient concentrations of 0.25, 0.5, 1, 2 μg / mL; when the active peptide amino acid sequence n=6, prepare gradient concentrations of 0.125, 0.25, 0.5, 1 μg / mL; when the active peptide amino acid sequence n=7, prepare gradient concentrations of 0.0625, 0.125, 0.25, 0.5 μg / mL).

[0051] At a 1:1 ratio, 500 μl of bacterial suspension (NaCl suspension) and 500 μl of active peptide solutions of different concentrations were respectively placed into 2 ml sterile EP tubes (final drug concentration 1×). The tubes were incubated at 37°C with shaking at 225 rpm for 3 h, centrifuged at 10000 rpm for 3 min, the supernatant was removed, and the bacterial cells in each EP tube were collected. The bacterial cells were resuspended in 1 ml of 0.85% sterile NaCl solution, centrifuged at 10000 rpm for 3 min, the supernatant was removed, and the bacterial cells were washed once. The bacterial cells were then resuspended in 0.3 ml of 0.85% sterile NaCl solution for later use. An equal volume of 2× Live / Dead working solution (provided by Thermo Fisher Scientific (China)) was added to 0.3 ml of the bacterial suspension, mixed thoroughly, and incubated at room temperature in the dark for 15 min. After incubation, the bacterial cells were washed three times with 1.5 ml of 0.85% sterile NaCl solution, and then resuspended in 0.5 ml of 0.85% sterile NaCl solution for flow cytometry analysis. The results are as follows: Figures 14 to 16 As shown.

[0052] The results showed that the active peptides at concentrations of 128 μg / mL, 2 μg / mL and 0.25 μg / mL had significant inhibitory effects on drug-resistant Escherichia coli, Staphylococcus aureus and Acinetobacter baumannii, with inhibition rates of approximately 98%.

[0053] Experimental Example 6 The ablation effects of the active peptides prepared in Examples 1-5 on different bacterial biofilms were determined.

[0054] First, the bacteria (drug-resistant Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii, stored at Anhui University of Technology (Wuhu, China)) were cultured in LB medium at 37°C until they reached the logarithmic growth phase (bacterial concentration of OD). 600 (OD600 = 0.6-0.8) Take 500 μl of bacterial culture from the culture tube and add it to 50 mL of fresh, sterile LB liquid medium. Incubate at 225 rpm and 37°C for 4 h to obtain a bacterial culture with an OD600 concentration between 0.6 and 0.8 (at which point the bacteria are in the logarithmic growth phase, and the bacterial cells are in optimal condition). Inoculate the bacterial culture into 96-well plates containing 0.25% glucose in LB medium (50 mL of LB liquid medium prepared with 0.5 g peptone, 0.25 g yeast extract, 0.5 g sodium chloride, and 1 g agar powder) and incubate at 37°C for 24 h to promote biofilm formation. Wash twice with PBS to remove residual culture medium, retaining the biofilm attached to the bottom of the wells. Different concentrations (100 μl each) of active peptide solution were added to each well and incubated for 30 min. The wells were then washed twice with PBS to remove excess peptide. The wells were then stained with 0.1% crystal violet solution for 15 min, followed by repeated washing to remove excess dye. The integrity of the biofilm was observed under a microscope, and the biofilm was dissolved in 33% acetic acid. The absorbance at 592 nm was measured to quantify the ablation effect of the peptide on the biofilm. Results are as follows: Figure 17 As shown.

[0055] The results showed that the active peptides at concentrations of 128 μg / mL, 2 μg / mL and 0.25 μg / mL had a significant ablation effect on the biofilms of drug-resistant Escherichia coli, Staphylococcus aureus and Acinetobacter baumannii, with ablation rates of approximately 98% in all cases.

[0056] Experimental Example 7 The hemolytic activity of the active peptides prepared in Examples 1-5 was determined.

[0057] RBC cells (fresh rat red blood cells, purchased from Nanjing Senbega Biotechnology Co., Ltd.) were washed three times with PBS and resuspended to prepare a 4% (v / v) RBC suspension. Different concentrations of active peptides (16, 32, 64, 128 μg / mL for n=3, 4, 8, 16, 32 μg / mL for n=4, 0.25, 0.5, 1, 2 μg / mL for n=5, 0.125, 0.25, 0.5, 1 μg / mL for n=6, and 0.0625, 0.125, 0.25, 0.25, 0.5, 0.5 μg / mL for n=7) were mixed with the RBC suspension and incubated at 37°C for 1 h, 12 h, and 24 h. After incubation, the samples were centrifuged at 3000 rpm for 10 min to separate intact red blood cells from lysed cells. The supernatant (containing released hemoglobin) was collected, and the absorbance was measured at 540 nm using a microplate reader. The hemolysis rate was calculated based on the absorbance values. PBS was used as a negative control, and 0.1% (v / v) Triton X-100 solution was used as a positive control. Results are as follows: Figure 18 As shown.

[0058] The results showed that the active peptides all exhibited good biocompatibility within 12 hours.

[0059] Experimental Example 8 The cytotoxicity of the active peptides prepared in Examples 1-5 was determined.

[0060] 293T cells (Wuhan Pronosai Life Science Technology Co., Ltd.) were used at a rate of 1×10⁻⁶. 4Cells were seeded at a density of 100 cells / well into 96-well plates and cultured in DMEM medium (Thermo Fisher) containing 10% fetal bovine serum. The plates were then incubated at 37°C in a 5% CO2 incubator until the cells reached 80% to 90% cell growth. Cells were co-incubated for 24 h with different concentration gradients of active peptides (16, 32, 64, 128 μg / mL for n=3, 4, 8, 16, 32 μg / mL for n=4, 0.25, 0.5, 1, 2 μg / mL for n=5, 0.125, 0.25, 0.5, 1 μg / mL for n=6, and 0.0625, 0.125, 0.25, 0.5, 0.5 μg / mL for n=7) of active peptides. After treatment, absorbance was measured at 570 nm using a microplate reader with a CCK-8 assay kit (Thermo Fisher). Results are as follows: Figure 19 As shown.

[0061] The results showed that the active polypeptide provided by the present invention had no significant cytotoxicity.

[0062] Experimental Example 9 To evaluate the killing ability of the active peptides prepared in Examples 1, 3, and 5 against cancer cells, HGC cells (gastric cancer cells, purchased from Wuhan Pronosai Life Science Technology Co., Ltd.) were subjected to a 1×10⁻⁶ ppm in vitro. 4 Cells were seeded at a density of [number] cells / well in 96-well plates and cultured in DMEM medium (Thermo Fisher) containing 10% fetal bovine serum. Cells were cultured at 37°C in a 5% CO2 incubator until 80%–90% confluence. Cells were then co-incubated with different concentration gradients of active peptides for 24 hours. After treatment, absorbance was measured at 570 nm using a microplate reader with a CCK-8 assay kit (Thermo Fisher). Results are as follows: Figure 20 As shown.

[0063] The results show that the Ac-G(K) provided by this invention dl I dl The killing ability of Ac-G(K) against gastric cancer cells varies with peptide chain length and exhibits a significant concentration dependence. Among them, Ac-G(K) dl I dl Ac-G(K) exhibits the strongest killing ability against gastric cancer cells, achieving a killing rate of approximately 85% at a concentration of 16 μg / mL and approximately 90% at concentrations of 32-128 μg / mL.dl I dl Ac-G(K)2 exhibits moderate killing activity against gastric cancer cells, achieving a killing rate of approximately 60% at a concentration of 64 μg / mL and approximately 90% at a concentration of 128 μg / mL. dl I dl 3-NH2 has a weak killing effect on gastric cancer cells.

[0064] As can be seen from the above embodiments, the present invention provides a class of active polypeptides and their applications. The active polypeptides can effectively inhibit the growth of drug-resistant Escherichia coli, Acinetobacter baumannii and Staphylococcus aureus, and have a good killing effect on gastric cancer cells HGC-27.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A class of active polypeptides characterized in that, The amino acid sequence of the active polypeptide is G(KI)n, 3≤n≤7, n is an integer.

2. The active polypeptide of claim 1, wherein, The active polypeptide has an acetylated amino terminal and an aminated carboxyl terminal.

3. The active polypeptide of claim 1, wherein, The active polypeptide is made of L-type amino acid and / or D-type amino acid.

4. The active polypeptide of claim 3, wherein, The L-type amino acid and / or D-type amino acid comprises one or more of isoleucine, lysine and glycine.

5. Use of the active polypeptide according to any one of claims 1-4 in the preparation of a bacteriostatic agent.

6. Use according to claim 5, characterized in that, The bacteriostatic agent has the effect of inhibiting drug-resistant Escherichia coli, Staphylococcus aureus and Acinetobacter baumannii.

7. Use of the active polypeptide according to any one of claims 1-4 in the preparation of a drug for resisting bacterial infection.

8. Use according to claim 7, characterized in that, The drug can inhibit the growth of drug-resistant Escherichia coli, Staphylococcus aureus and Acinetobacter baumannii.

9. Use of the active polypeptide according to any one of claims 1-4 in the inhibition of bacteria.

10. Use of the active polypeptide according to any one of claims 1-4 in the preparation of a drug for resisting tumors.

Images