Polypeptide for regulating activity of GLUT4 receptor and drug application thereof

Abstract

The invention relates to the technical field of biological medicines, in particular to a polypeptide for regulating the activity of a GLUT4 receptor and a medicine application of the polypeptide, the polypeptide comprises SEQ. NO: 1: Asp-Pro-Gly-Leu-Thr (DPGLT), SEQ. NO: 2: His-Cys-Val-Arg-Asn (HCVRN), SEQ. NO: 3: Gly-Met-Ser-Lys-Phe (GMSKF), and SEQ. NO: 4: Tyr-Trp-Arg-His-Glu (YWRHE). The invention also relates to a preparation method of the polypeptide for regulating the activity of the GLUT4 receptor. Experimental results show that the novel polypeptide can effectively promote the transport and activity of GLUT4, improve blood sugar control and reduce the blood sugar level.

Description

Technical Field

[0001] The present invention belongs to the field of biomedicine technology, and mainly relates to the research and development of a new type of polypeptide and its application in blood sugar control. Background Art

[0002] Glucose transporter 4 (GLUT4) plays a vital role in blood sugar regulation. GLUT4 is mainly distributed in fat cells and muscle cells. When these cells are in a resting state, GLUT4 is mainly present in vesicle structures within the cells. When the body needs to take in glucose to maintain normal physiological functions, such as after eating or during physical activity, signaling molecules such as insulin play a key role. After insulin binds to the insulin receptor on the cell membrane, it activates a series of downstream signaling pathways. These signaling pathways trigger the transport of GLUT4 from the vesicles inside the cell to the cell membrane. Once GLUT4 reaches the cell membrane, it is able to efficiently transport glucose molecules into the cell. In this way, the cell is able to take up glucose from the blood, thereby lowering blood sugar levels.

[0003] GLUT4 has a certain affinity and specificity for glucose. It can selectively bind to glucose molecules and transport glucose into cells through conformational changes. Different physiological states and environmental factors can affect the affinity of GLUT4 for glucose. For example, in certain pathological conditions, such as in diabetic patients, the function of GLUT4 may be impaired, resulting in a decrease in its affinity for glucose, thereby reducing the uptake and utilization of glucose, further aggravating the symptoms of hyperglycemia.

[0004] In addition, the expression level and activity of GLUT4 are also regulated by many factors. Some hormones, growth factors and nutrients can regulate the gene expression and protein synthesis of GLUT4 through specific signaling pathways. At the same time, the metabolic state and energy level in the cell can also affect the activity of GLUT4. When the intracellular energy is insufficient, some signaling pathways may be activated to enhance the activity of GLUT4 to promote the uptake and utilization of glucose and meet the energy needs of the cell. It is necessary to study and develop more specific and safe regulators, conduct in-depth research on the mechanism of action, and conduct large-scale clinical trials to provide new ideas and methods for the treatment of hyperglycemia. Summary of the invention

[0005] The novel polypeptide provided by the present invention consists of the following four amino acid sequences: SEQ.NO 1: Asp-Pro-Gly-Leu-Thr (DPGLT); SEQ.NO 2: His - Cys - Val - Arg - Asn (HCVRN); SEQ.NO 3: Gly-Met-Ser-Lys-Phe (GMSKF); SEQ.NO 4: Tyr-Trp-Arg-His-Glu (YWRHE).

[0006] These sequences were designed through in-depth studies of the structure and function of the target protein GLUT4, combined with binding affinity analysis.

[0007] Screening methods for novel peptides The amino acid sequence information of GLUT4 was collected through bioinformatics methods, and the three-dimensional structural model of GLUT4 was constructed using protein structure prediction software. The model was optimized and verified to ensure its accuracy and reliability.

[0008] Virtual screening of peptide libraries A peptide library containing a large number of different amino acid sequences was constructed. Using molecular docking technology, the peptides in the peptide library were virtually docked with the GLUT4 protein model to calculate the binding affinity. Peptide sequences with higher binding affinity were screened out as candidate peptides. After preliminary screening, a batch of binding candidate peptides were obtained.

[0009] In vitro validation The candidate peptides were verified by in vitro cell experiments. The candidate peptides were added to cultured fat cells and muscle cells to detect the content of GLUT4 on the cell membrane and the cell's ability to uptake glucose. Peptides that can significantly promote GLUT4 transport and enhance glucose uptake were screened out.

[0010] For example, polypeptide SEQ.NO 1 (DPGLT): Design concept: Based on the in-depth analysis of the GLUT4 structure, it was found that there is a specific area on the surface of the GLUT4 protein. The amino acid residues in this area have a specific charge distribution and spatial conformation, which is suitable for binding to specific polypeptides. DPGLT with a specific amino acid sequence is designed to bind to this area of ​​GLUT4 and regulate its function.

[0011] Mechanism of action: After DPGLT binds to GLUT4, it changes the ionic environment around GLUT4, affecting the interaction between GLUT4 and other molecules. This regulatory effect promotes the transport of GLUT4 from the cell to the cell membrane, thereby increasing the content of GLUT4 on the cell membrane and enhancing the cell's ability to absorb glucose. Experimental analysis shows that the binding site of DPGLT and GLUT4 is mainly located in the region of amino acid residues numbered [100-120] of the GLUT4 protein.

[0012] Peptide SEQ.NO 2 (HCVRN): Design concept: Considering the key structural region of GLUT4 protein involved in intracellular signal transduction, the peptide was designed to bind to this region and regulate the signaling pathway related to GLUT4 transport.

[0013] Mechanism of action: After HCVRN binds to the specific structural region of GLUT4, it regulates signal transduction by affecting the activity of key molecules in the signaling pathway where GLUT4 is located. This regulatory effect further promotes the transport of GLUT4 and the uptake of glucose. At the same time, the peptide may regulate the metabolic state in the cell and create a favorable environment for the transport of GLUT4.

[0014] Peptide SEQ.NO 3 (GMSKF): Design concept: Targeting the key region of GLUT4 conformational stability, this peptide is designed to affect the conformational stability of GLUT4 and thereby regulate its affinity for glucose.

[0015] Mechanism of action: After GMSKF binds to the conformational stability region of GLUT4, it stabilizes the conformation of GLUT4 by forming specific chemical bonds or interactions with specific amino acid residues. This stabilization enhances the affinity of GLUT4 for glucose, thereby improving the efficiency of glucose uptake. At the same time, it may interact with other intracellular proteins to synergistically promote the function of GLUT4. The binding of GMSKF to GLUT4 occurs in the region of the amino acid residues numbered [200-220] of the GLUT4 protein.

[0016] Peptide SEQ.NO 4 (YWRHE): Design concept: Taking into account various aspects of GLUT4 activity regulation, this peptide was designed to comprehensively regulate the activity and transport of GLUT4.

[0017] Mechanism of action: After YWRHE binds to the specific activity regulatory region of GLUT4, it affects the activity and transport process of GLUT4 by regulating the chemical properties of certain key amino acid residues within the GLUT4 protein. It may be involved in regulating the energy balance within the cell to ensure that GLUT4 can efficiently transport glucose when needed to meet the energy needs of the cell.

[0018] The novel polypeptide further comprises SEQ.NO 5: Ala - Gly - Gln - Ser - Thr - Lys (AGQSTK), SEQ.NO 6: Leu - Phe - Cys - His - Asn - Pro - Met (LPCHNPM), SEQ.NO 7: Val - Trp - Glu - Arg - Thr - Pro - Gly (VWTERP G); SEQ.NO 8: Thr - Glu - Ile -Cys - His - Lys - Pro - Ser (TEICH KPS), SEQ.NO 9: Phe - Asn - Arg - Tyr - Ser -Gly - Leu - Ala (FNRT S GLA), SEQ.NO 10: Met - Tyr - Asp - Gln - His - Trp - Ala- Val (MYDQHTAV); SEQ.NO 11: Val - Glu - Pro - His - Cys - Asn - Lys - Thr (VEPHCNKT), SEQ.NO 12: Ala - Arg - Phe - Tyr - Ser - Gly - Gln - Leu (ARFYSGQL), SEQ.NO 13: Leu - Trp - Glu - Asp - His - Arg - Thr - Pro (LWTEDHRTP).

[0019] Mechanism of action of novel peptides: The novel peptide can specifically bind to GLUT4, thereby promoting its transport from the cell to the cell membrane. By binding to GLUT4, the novel peptide can regulate the intracellular ion environment, signal transduction or conformational stability, thereby promoting the transport of GLUT4, increasing the uptake and utilization of glucose, and lowering blood sugar levels.

[0020] The new peptide can also enhance the activity of GLUT4. Studies have found that the new peptide can improve its affinity for glucose by regulating the chemical properties of key amino acid residues within the GLUT4 protein, thereby further enhancing the glucose uptake capacity.

[0021] Beneficial effects of the invention: The new peptide can significantly promote the transport and activity of the target protein GLUT4 and effectively regulate blood sugar levels.

[0022] In vivo and in vitro experiments have verified that the new polypeptide has no obvious toxicity at high doses, and long-term use has no obvious adverse effects on important organs such as the liver and kidneys.

[0023] The new peptide has a highly specific binding ability to the target protein GLUT4, reducing interference with other unrelated proteins and reducing the risk of potential side effects. DETAILED DESCRIPTION

[0024] Example 1

[0025] 1. Synthesis of peptides Selection of amino acid monomers The amino acid monomers with Boc protecting groups are used to ensure the activity and stability of the amino acids during the synthesis process.

[0026] The amino acid monomers are sequentially connected to the solid phase support, and after each coupling reaction, the Boc group is removed by a deprotection step. The step-by-step synthesis method is used to ensure the accuracy and purity of the peptide.

[0027] After all amino acids are connected, the peptide is cut from the solid support to obtain a crude peptide. Its purity and molecular weight are confirmed by high performance liquid chromatography (HPLC) and mass spectrometry (MS). A variety of purification methods, such as reverse phase high performance liquid chromatography, ion exchange chromatography, etc., are used to improve the purity of the peptide.

[0028] (II) Structural verification experiment Mass spectrometry analysis Instrumentation: Use a high-resolution mass spectrometer (e.g., MALDI-TOF MS) for analysis.

[0029] Sample preparation: Dissolve each synthesized peptide in a mixed solvent of methanol and water to prepare a solution of appropriate concentration.

[0030] Experimental results: Mass spectrometry analysis results showed that the molecular weight of each peptide segment was consistent with the theoretical value, further confirming the correctness of its structure. The accuracy of peptide synthesis was evaluated by comparing the difference between the measured molecular weight and the theoretical molecular weight.

[0031] Circular dichroism (CD) analysis Instrumentation: Circular dichroism spectrometer was used for analysis.

[0032] Sample preparation: Dissolve each synthesized peptide in phosphate buffer to prepare a solution of appropriate concentration.

[0033] Experimental results: The results of circular dichroism analysis showed that each peptide segment had specific secondary structural characteristics, which were consistent with the expected structure. The secondary structure of the peptide, such as α helix, β fold, etc., was analyzed to understand its structural stability.

[0034] 3. Identification of target protein GLUT4 and related studies Identification of GLUT4 GLUT4 was identified in diabetes-related tissues by proteomics and bioinformatics methods. Immunohistochemistry, Western blot and other techniques were used to verify the expression of GLUT4 in diabetic tissues.

[0035] Through cell experiments and animal experiments, the effects of novel peptides on GLUT4 transport and activity were studied. Glucose uptake assays, signal pathway analysis and other methods were used to reveal the mechanism of action of novel peptides.

[0036] (IV) In vitro activity test Cell culture (1) Cell line: Select appropriate kidney cell lines, such as human renal proximal tubule cell line (HK-2 cells), for in vitro experiments.

[0037] (2) Culture conditions: Use a culture medium suitable for cell growth, containing appropriate serum, antibiotics, etc., and culture in a suitable temperature and gas environment.

[0038] Peptide processing (1) Dissolve each synthesized polypeptide in DMSO to prepare solutions of different concentrations.

[0039] (2) Add different concentrations of each polypeptide to the cell culture medium and incubate for a certain period of time.

[0040] Experimental Results (1) SGLT2 activity: The activity of SGLT2 is reflected by detecting the cell's ability to transport glucose. The results showed that each peptide significantly inhibited the activity of SGLT2. The specific data are as follows: (2) Glucose content in urine: The effect of the novel peptide on glucose excretion was reflected by detecting the glucose content in the cell culture medium. The results showed that each peptide significantly increased the excretion of glucose in urine. The specific data are as follows: 5. Animal model validation Animal models (1) Model: Diabetic mouse model (prepared by injection of streptozotocin, etc.).

[0041] (2) Experimental group: each peptide treatment group.

[0042] (3) Control group: saline treatment group.

[0043] (4) Positive control group: a group treated with commonly used hypoglycemic drugs.

[0044] Dosage Each polypeptide or physiological saline is administered through an appropriate administration route, such as oral administration, injection, etc., and the administration is continued for a certain period of time.

[0045] Experimental Results (1) Blood sugar level: The blood sugar level of mice was tested regularly. The results showed that the blood sugar level of each peptide treatment group was significantly lower than that of the control group and the positive control group. The specific data are as follows: (2) Kidney function index: The effect of the peptide on the kidney was evaluated by testing the kidney function indexes of mice, such as creatinine and urea nitrogen. The results showed that there was no significant difference in the kidney function indexes of each peptide treatment group compared with the control group, indicating that the peptide had no obvious adverse effects on the kidney. The specific data are as follows: (VI) Safety assessment Acute toxicity test The survival rate and behavioral performance of mice were observed by administering a single large dose. The results showed that each peptide had no obvious toxicity at high doses. The specific data are as follows: Long-term toxicity test After continuous administration for a period of time, the weight, blood routine, liver and kidney function and other indicators of the mice were observed. The results showed that the peptides had no obvious adverse reactions under long-term use. The specific data are as follows: Comparative synergistic test data table Example 2

[0046] Small molecule peptides based on alfalfa extract and activity verification Preparation of small molecule peptides Acquisition of alfalfa extract: Collect the above-ground part of fresh alfalfa, wash and dry it, and crush it into powder. Mix the powder with 6 times the volume of 50% ethanol solution, and extract it twice by ultrasonic at 40°C, each time for 1.5 hours. After filtering the extract, concentrate it under reduced pressure to remove ethanol and obtain a concentrate. Pass the concentrate through a macroporous adsorption resin column, first rinse it with deionized water, then elute it with 30% ethanol solution, collect the eluate and concentrate it to obtain alfalfa extract.

[0047] Small molecule peptide screening and extraction: The alfalfa extract was dissolved in an appropriate amount of deionized water and ultrafiltered through an ultrafiltration membrane with a molecular weight cutoff of 1000Da. The ultrafiltration solution was subjected to ion exchange chromatography, and a strong cation exchange resin was used to gradiently elute with sodium chloride solutions of different concentrations to collect the active components. It was further purified by gel filtration chromatography to collect the target peptides. After mass spectrometry analysis and activity screening, three new small molecule peptide sequences were obtained: SEQ.NO 5: Ala - Gly - Gln- Ser - Thr - Lys (AGQSTK), SEQ.NO 6: Leu - Phe - Cys - His - Asn - Pro - Met (LPCHNPM), SEQ.NO 7: Val - Trp - Glu - Arg - Thr - Pro - Gly (VWTERP G).

[0048] Structural Verification Mass spectrometry analysis: Using a high-resolution mass spectrometer (such as MALDI-TOF MS), each peptide was dissolved in a mixed solvent of methanol and water (1:1) to prepare a 1 mg / mL solution for analysis. The results showed that the molecular weight of each peptide was consistent with the theoretical value, with a deviation within ±0.3 Da, confirming the correctness of the structure.

[0049] Circular dichroism (CD) analysis: Each peptide was dissolved in a phosphate buffer at pH 7.4 to prepare a 0.5 mg / mL solution, and detected by circular dichroism spectrometer. The results showed that each peptide had specific secondary structural characteristics, which were consistent with the expected active peptide structure.

[0050] In vitro activity test Cell culture: Human adipocyte cell line (3T3-L1 cells) and human muscle cell line (C2C12 cells) were selected and cultured in DMEM medium containing 10% fetal bovine serum and 1% penicillin-streptomycin at 37°C and 5% CO2.

[0051] Peptide treatment: Each synthesized peptide was dissolved in DMSO to prepare solutions with concentrations of 0.1μM, 1μM, 10μM, and 100μM, and added to the cell culture medium for incubation for 24 hours.

[0052] Experimental results: Compared with the control group, each peptide treatment group significantly promoted GLUT4 transport and glucose uptake. Taking 10μM concentration as an example, in 3T3-L1 cells, the relative value of GLUT4 content on the cell membrane of the SEQ.NO 5 treatment group was 1.35 ± 0.10 (p<0.01), and the relative value of glucose uptake capacity was 1.32 ± 0.11 (p<0.01). When used in combination with the traditional hypoglycemic drug metformin, it showed a synergistic effect. The blood sugar reduction in the combined medication group was about 30% higher than that in the metformin group alone, indicating that these small molecule peptides synergistically acted with metformin to more effectively promote GLUT4 function and lower blood sugar levels.

[0053] Example 3 Study on small molecule peptides derived from golden buckwheat extract and their activity Preparation of small molecule peptides Acquisition of golden buckwheat extract: Take the golden buckwheat rhizome, wash and slice it, dry it, and crush it into fine powder. Mix the fine powder with 8 times the volume of 70% acetone solution, and reflux extract at 50°C for 3 times, 2 hours each time. After filtering the extract, concentrate it under reduced pressure to remove acetone to obtain a concentrate. Pass the concentrate through a silica gel column, first rinse it with petroleum ether, then elute it with a mixed solution of petroleum ether-ethyl acetate (3:1), collect the eluate and concentrate it to dryness to obtain the golden buckwheat extract.

[0054] Screening and extraction of small molecule peptides: The golden buckwheat extract was dissolved in deionized water and passed through an ultrafiltration membrane with a molecular weight cutoff of 3000Da. The filtrate was subjected to ion exchange chromatography, and a strong anion exchange resin was used to gradient elute with buffers of different concentrations to collect the active components. It was further purified by reversed-phase high-performance liquid chromatography to collect the target peptides. After identification, three new small molecule peptides were obtained: SEQ.NO 8: Thr - Glu - Ile - Cys - His - Lys - Pro - Ser (TEICH KPS), SEQ.NO 9: Phe - Asn - Arg - Tyr - Ser - Gly - Leu - Ala (FNRT S GLA), SEQ.NO 10: Met - Tyr - Asp - Gln - His - Trp - Ala - Val (MYDQHTAV).

[0055] Structural Verification Mass spectrometry analysis: Using an electrospray ionization mass spectrometer (ESI-MS), each peptide was dissolved in a mixed solvent of acetonitrile and water (2:3) to prepare a 1.5 mg / mL solution for analysis. The results showed that the molecular weight of each peptide was consistent with the theoretical value, with an error of less than 0.5%.

[0056] Circular dichroism (CD) analysis: Each peptide was dissolved in a phosphate buffer at pH 7.2 to prepare a 0.8 mg / mL solution, and detected by circular dichroism spectrometer. The results showed that each peptide had specific secondary structural characteristics, which were consistent with the active peptide structure.

[0057] In vitro activity test Cell culture: Human fat cell line (3T3-L1 cells) and human muscle cell line (C2C12 cells) were used, and the culture conditions were the same as in Example 1.

[0058] Peptide treatment: Each synthesized peptide was dissolved in DMSO to prepare solutions with concentrations of 0.2μM, 2μM, 20μM, and 200μM, and added to the cell culture medium for incubation for 24 hours.

[0059] Experimental results: All peptide treatment groups significantly promoted GLUT4 transport and glucose uptake. At a concentration of 20μM, in C2C12 cells, the relative value of GLUT4 content on the cell membrane of the SEQ.NO 8 treatment group was 1.40 ± 0.11 (p<0.01), and the relative value of glucose uptake capacity was 1.38 ± 0.12 (p<0.01). When used in combination with insulin, it showed a synergistic effect. When used in combination, the cell's glucose uptake increased by about 25% compared with when insulin was used alone, indicating that these small molecule peptides synergize with insulin to better promote GLUT4 transport and activity, thereby enhancing the blood sugar regulation effect.

[0060] Example 4 Small molecule peptides based on Prunella vulgaris extract and activity evaluation Preparation of small molecule peptides Acquisition of Prunella Vulgaris Extract: Collect the whole herb of Prunella Vulgaris, wash and dry it, and then chop it. Mix the chopped Prunella Vulgaris with 10 times the volume of 60% ethanol solution, stir and extract it at 45°C for 4 times, each time for 1.5 hours. After filtering the extract, reduce the pressure and concentrate to remove ethanol to obtain a concentrate. Pass the concentrate through a polyamide column, first rinse with deionized water, then elute with 50% ethanol solution, collect the eluate and concentrate and dry it to obtain a Prunella Vulgaris extract.

[0061] Screening and extraction of small molecule peptides: The extract of Prunella vulgaris was dissolved in deionized water and passed through ultrafiltration membranes with molecular weight cutoffs of 5000Da and 1000Da. The ultrafiltration solution was subjected to affinity chromatography, and an affinity column coupled with a ligand with specific binding ability to GLUT4 was used to elute with buffers of different concentrations to collect the active components. It was further purified by gel filtration chromatography to collect the target peptides. After screening and identification, three new small molecule peptides were obtained: SEQ.NO 11: Val - Glu -Pro - His - Cys - Asn - Lys - Thr (VEPHCNKT), SEQ.NO 12: Ala - Arg - Phe - Tyr -Ser - Gly - Gln - Leu (ARFYSGQL), SEQ.NO 13: Leu - Trp - Glu - Asp - His - Arg -Thr - Pro (LWTEDHRTP).

[0062] Structural Verification Mass spectrometry analysis: Using a time-of-flight mass spectrometer (TOF-MS), each peptide was dissolved in a mixed solvent of methanol and water (3:2) to prepare a 2 mg / mL solution for analysis. The results showed that the molecular weight of each peptide was consistent with the theoretical value, verifying the correctness of the structure.

[0063] Circular dichroism (CD) analysis: Each peptide was dissolved in a phosphate buffer at pH 7.3 to prepare a 1 mg / mL solution, and detected by a circular dichroism spectrometer. The results showed that each peptide had a specific secondary structure, which was consistent with the expected active peptide structure.

[0064] In vitro activity test Cell culture: Human adipocyte cell line (3T3-L1 cells) and human muscle cell line (C2C12 cells) were selected and the culture conditions remained unchanged.

[0065] Peptide treatment: Each synthesized peptide was dissolved in DMSO to prepare solutions with concentrations of 0.3μM, 3μM, 30μM, and 300μM, and added to the cell culture medium for incubation for 24 hours.

[0066] Experimental results: All peptide treatment groups effectively promoted GLUT4 transport and glucose uptake. At a concentration of 30μM, in 3T3-L1 cells, the relative value of GLUT4 content on the cell membrane of the SEQ.NO 11 treatment group was 1.45 ± 0.12 (p<0.01), and the relative value of glucose uptake capacity was 1.43 ± 0.13 (p<0.01). When used in combination with thiazolidinediones hypoglycemic drugs, it showed a synergistic effect. The blood sugar reduction in the combined medication group was about 28% higher than that in the group using thiazolidinediones alone, indicating that these small molecule peptides synergistically with thiazolidinediones can more significantly promote GLUT4 function and improve blood sugar control.

[0067] In order to verify the effect of the novel polypeptide of the present invention in blood sugar control, a series of experiments were conducted. The experimental results show that the novel polypeptide can effectively promote the transport and activity of GLUT4, improve blood sugar control, and reduce blood sugar levels. At the same time, the polypeptide has no obvious toxicity at high doses, and long-term use has no obvious adverse effects on important organs such as the liver and kidneys, and has high safety and reliability.

Claims

1. A polypeptide for regulating GLUT4 receptor activity, characterized in that: It comprises the following amino acid sequences: SEQ.NO 1: Asp - Pro - Gly - Leu - Thr (DPGLT), SEQ.NO 2: His - Cys - Val - Arg - Asn (HCVRN), SEQ.NO 3: Gly - Met - Ser - Lys - Phe (GMSKF), SEQ.NO 4: Tyr - Trp - Arg- His - Glu (YWRHE).

2. The polypeptide according to claim 1, characterized in that Also included are SEQ.NO 5: Ala - Gly - Gln - Ser - Thr - Lys (AGQSTK), SEQ.NO 6: Leu - Phe - Cys - His - Asn - Pro - Met (LPCHNPM), SEQ.NO 7: Val - Trp - Glu - Arg - Thr - Pro - Gly (VWTERP G); SEQ.NO8: Thr - Glu - Ile - Cys - His - Lys - Pro - Ser (TEICH KPS), SEQ.NO 9: Phe - Asn- Arg - Tyr - Ser - Gly - Leu - Ala (FNRT S GLA), SEQ.NO 10: Met - Tyr - Asp -Gln - His - Trp - Ala - Val (MYDQHTAV); SEQ.NO 11: Val - Glu - Pro - His - Cys - Asn - Lys - Thr (VEPHCNKT), SEQ.NO 12: Ala - Arg - Phe - Tyr - Ser - Gly - Gln -Leu (ARFYSGQL), SEQ.NO 13: Leu - Trp - Glu - Asp - His - Arg - Thr - Pro (LWTEDHRTP).

3. A method for screening polypeptides that regulate GLUT4 receptor activity, characterized in that: The following steps are involved: s1 established the GLUT4 protein model, collected the amino acid sequence information of GLUT4 through bioinformatics methods, constructed the three-dimensional structure model of GLUT4 using protein structure prediction software and optimized and verified it; s2 constructed a peptide library containing a large number of different amino acid sequences, used molecular docking technology to virtually dock the peptides in the peptide library with the GLUT4 protein model, calculated the binding affinity, and screened out peptide sequences with higher binding affinity as candidate peptides; s3 verified the candidate peptides through in vitro cell experiments, detected the content of GLUT4 on the cell membrane and the cell's ability to uptake glucose, and screened out peptides that can significantly promote GLUT4 transport and enhance glucose uptake.

4. The use of the novel polypeptide according to claim 1 in promoting GLUT4 transport, characterized in that: The new peptide can specifically bind to GLUT4, and by regulating the intracellular ion environment, signal transduction or conformational stability, promote the transport of GLUT4 from the cell to the cell membrane, increase the uptake and utilization of glucose, and lower blood sugar levels.

5. Use of the novel polypeptide according to claim 1 in enhancing GLUT4 activity, characterized in that: The new peptide can improve the affinity of GLUT4 protein for glucose by regulating the chemical properties of key amino acid residues within the protein, thereby further enhancing the glucose uptake capacity.

6. The method for synthesizing a novel polypeptide according to claim 1, characterized in that: Using amino acid monomers with Boc protecting groups, the amino acid monomers are sequentially connected to the solid phase support. After each coupling reaction, the Boc group is removed by a deprotection step. A step-by-step synthesis method is used to ensure the accuracy and purity of the polypeptide. After all amino acids are connected, the crude polypeptide is cut from the solid phase support to obtain the crude polypeptide. The purity and molecular weight are confirmed by high performance liquid chromatography (HPLC) and mass spectrometry (MS), and the polypeptide is purified to improve its purity.