492 results about "Leucines" patented technology

The invention discloses a high-performance carbonyl reductase mutant and application thereof in synthesis of a series of chiral alcohols. The high-performance carbonyl reductase mutant is obtained by performing the following mutations on an amino acid sequence as shown in SEQ ID NO.2: the 69th alanine mutates into any one of lysine, leucine, aspartic acid or asparagine, and the 69th alanine mutates into any one of lysine, leucine, aspartic acid or asparagine; and / or the 100th glycine is mutated into any one of glutamic acid, serine, lysine or asparagine. Compared with a wild type enzyme, the thermal stability and the catalytic activity of the obtained mutant are remarkably improved, particularly, single point mutants Mut-A69N, Mut-G100E and Mut-G100N and a combined mutant Mut-A69N-G100N show excellent relative enzyme activity, thermal stability and substrate tolerance. The mutant has high catalytic activity and stability to various chiral alcohols, and the contradiction that the traditional carbonyl reductase is easy to inactivate at high temperature and the catalytic efficiency is difficult to achieve at the same time is solved. The invention provides an efficient and stable enzyme catalysis tool for green biological preparation of chiral drug intermediates.

The invention relates to the technical field of biological catalysis, and discloses an L379A mutant enzyme for preparing rebaudioside I. The enzyme is obtained by the following mutations generated by UGT76G1: leucine of the 379th amino acid sequence is mutated into alanine; the enzyme can be applied to RA in-vitro conversion preparation of RI with higher utilization value, the conversion rate is higher than 50%, and the enzyme activity is remarkably improved by 7 times compared with the original enzyme catalytic conversion enzyme activity. The UGT76G1 mutant disclosed by the invention has the advantages that (1) the blank is filled, and a special enzyme catalyst capable of realizing efficient in-vitro synthesis of rebaudioside I (RI) is provided for the first time; 2) efficiency jump: the catalytic conversion rate is greatly increased from original about 7% to more than 50% (increase gt; and 3) stability and reliability: in the cross-scale reaction of 10mL to 5L, the catalyst has stable catalytic performance, shows excellent industrial application potential, and is suitable for popularization and application.

The present disclosure provides methods of treating a neurodevelopmental disorder (NDD) in a subject by administering a therapeutically effective amount of N-acetyl leucine.

The invention belongs to the technical field of genetic engineering and enzyme engineering, and particularly relates to a genetically engineered bacterium for stably and efficiently producing L-isoleucine as well as a construction method and application of the genetically engineered bacterium. The genetically engineered bacterium takes E. coliTHRD as a host and contains an RNA (Ribonucleic Acid) polymerase beta-subunit mutant coding gene rpoBM; compared with a parent RNA polymerase beta-subunit, the RNA polymerase beta-subunit mutant has the advantage that the amino acid residue at the 618th site of the amino acid sequence is sequentially replaced with leucine from the N terminal to the C terminal. The genetically engineered bacterium disclosed by the invention can tolerate L-isoleucine and accumulate less alpha-ketobutyric acid, and has a very good industrial application prospect.

The invention belongs to the technical field of bioengineering, and relates to a transaminase mutant, a recombinant genetically engineered bacterium and application of the transaminase mutant in catalytic synthesis of (R)-1-Boc-3-aminopiperidine.The transaminase mutant is obtained by conducting single-point or combined mutation on the 131 site and / or the 197 site of an amino acid sequence shown in SEQ ID NO.2; the mutation sites comprise that the 131 phenylalanine is mutated into aspartic acid, threonine or tyrosine, and / or the 197 lysine is mutated into arginine or leucine. Experimental results show that compared with wild type transaminase, the catalytic activity, the thermal stability and the organic solvent tolerance of the obtained mutants, especially single-point mutants MyTA1-F131Y and MyTA1-K197R and a combined mutant MyTA1-F131Y-K197R, are all remarkably improved, and compared with the wild type transaminase, the catalytic activity, the thermal stability and the organic solvent tolerance of the obtained mutants are all remarkably improved. The mutant MyTA1-F131Y-K197R can be used for efficiently catalyzing asymmetric amination of N-Boc-3-piperidone to synthesize (R)-1-Boc-3-aminopiperidine, the conversion rate of the (R)-1-Boc-3-aminopiperidine after the (R)-1-Boc-3-aminopiperidine reacts for 24 hours under the condition that the substrate concentration is 100 g / L can reach 90% or above, and the mutant MyTA1-F131Y-K197R has a good industrial application prospect.

The invention relates to the technical field of biological catalysis, and discloses an L204A mutant enzyme for preparing rebaudioside I. The enzyme is obtained by the following mutations generated by UGT76G1: L204A: leucine of the 204 amino acid sequence of UGT76G1 mutates into alanine; the high-efficiency in-vitro enzymatic preparation of the rebaudioside I (RI) is realized for the first time, the catalytic efficiency of the rebaudioside I (RI) is improved by more than 7 times (from about 7% to more than or equal to 50%) compared with that of an original enzyme, the high-efficiency performance can be stably maintained under different scales of 10mL to 5L, a solid foundation is laid for industrial application of the RI, and the preparation method is simple, controllable in process condition and suitable for popularization and application.

The invention discloses a method for inhibiting production of vomitoxin from bacillus cereus, which is characterized in that isoleucine is added into a substance needing to inhibit production of vomitoxin from bacillus cereus, preferably 5-20mM of isoleucine is added. According to the present invention, the content of the toxin is detected through the liquid chromatography-mass spectrometry, and the cytotoxicity experiment verification results show that the isoleucine can significantly inhibit the synthesis of the vomitoxin of the bacillus cereus in the culture medium and the matrix, and can effectively reduce the toxic effect of the toxin on HeLa cells; the invention provides a safe and efficient biological control means which is suitable for various food systems such as starch food, dairy products, meat products and the like. Isoleucine can be used as a novel non-toxic and harmless food additive and is low in cost; the use method is simple, the output of vomitoxin can be reduced by directly adding a trace amount of isoleucine, and the food flavor is not affected.

The invention discloses a high-stability carbonyl reductase mutant and application of the high-stability carbonyl reductase mutant in chiral alcohol synthesis. An amino acid sequence as shown in SEQ ID NO.2 is mutated as follows: 20th leucine is replaced by any one of lysine, threonine, aspartic acid or isoleucine, and / or 55th leucine is replaced by any one of methionine, serine, lysine or isoleucine, and / or 55th leucine is replaced by any one of methionine, serine, lysine or isoleucine. Compared with a wild type enzyme, the stability of the obtained mutant is remarkably improved, particularly, single-point mutants Mut-L20I and Mut-L55I and a combined mutant Mut-L20I-L55I show excellent relative enzyme activity, thermal stability and substrate tolerance. The mutant has high catalytic activity and stability to various chiral alcohols, has the advantages of high catalytic efficiency, high thermal stability, strong substrate tolerance, easiness in fermentation production and the like, and is suitable for industrial application of enzymatic synthesis of chiral alcohols.

The invention belongs to the field of plant genetic engineering, and discloses a key gene OsHPCA1 for positively regulating salt stress and oxidative stress tolerance of rice. The gene (with the login number of Os05g40770) encodes a receptor protein capable of specifically sensing hydrogen peroxide, and belongs to a leucine repeat receptor-like protein kinase (LRR-RLKs) family, wherein the family is the largest subfamily in the receptor-like protein kinase (RLKs). The OsHPCA1 responds to salt and oxidative stress signals, and the salt tolerance and oxidative stress resistance of the rice are positively regulated and responded. The OsHPCA1 overexpression rice strain shows very strong salt tolerance; and the OsHPCA1 knockout strain oshpca1 is more sensitive to salt stress. The OsHPCA1 protein encoded by the OsHPCA1 gene and rich in leucine repeat receptor-like protein kinase can positively regulate and control the activity of catalase C (CatC) in rice and enhance the removal efficiency of H2O2 under salt stress, so that the salt tolerance of rice is improved. When the OsHPCA1 is overexpressed, the activity of CatC in the overexpressed strain OsHPCA1 is obviously increased, the H2O2 removal capability is enhanced, and the salt tolerance and oxidative stress tolerance of the rice are improved.

The invention provides a strain for producing L-isoleucine as well as a construction method and application thereof. The strain is obtained by modifying a chassis strain escherichia coli XX12 by utilizing a metabolic engineering modification method, ldhA, adhE and pflB genes are deleted, the transcriptional levels of aspC, pykF, pntAB, ppK, ppc, ilvAfbr, ilvIHfbr and ygaZH genes are up-regulated, the transcriptional level of a leuA gene is down-regulated, a bcd gene derived from B.subtilis 168 and ppnK and cysK genes derived from Cornebacterium glutamicum ATCC 13032 are heterologously expressed, and the strain has the advantages that the strain can be used for producing L-isoleucine; the method has the advantages of no need of adding resistant substances, good L-isoleucine synthesis capability, short fermentation period by using glucose as a carbon source, and good economic benefit and industrial application value.

The invention discloses an amino acid composition for treating alopecia and application of the amino acid composition in preparation of a medicine for treating alopecia, and belongs to the field of medicine configuration products, the amino acid composition is composed of a targeting core intervention component and an auxiliary strengthening synergistic component, the targeting core intervention component is prepared from 30-50 parts of arginine, 50-155 parts of lysine and 50-120 parts of glutamic acid, and the auxiliary strengthening synergistic component is prepared from an auxiliary strengthening synergistic component and an auxiliary strengthening synergistic component. 10 to 40 parts of cysteine and 20 to 60 parts of leucine; the auxiliary strengthening synergistic component is prepared from 15 to 45 parts of tyrosine, 15 to 40 parts of glycine, 10 to 40 parts of glutamine, 20 to 35 parts of serine, 5 to 25 parts of alanine, 2 to 20 parts of aspartic acid and 15 to 35 parts of phenylalanine; the composition can be used as an active ingredient to be prepared into different dosage forms such as a pigmentum, a spray, an ointment and a liniment, is applied to prevention of alopecia and promotion of hair growth, and has a remarkable treatment effect.

The present disclosure is directed to HLA class II molecules having a higher affinity for CD4 than naturally occurring HLA class II molecules. In certain aspects, the HLA class II molecule comprises a DQ beta chain having (i) an amino acid other than leucine at a position corresponding to amino acid residue 114 of SEQ ID NO: 1, (ii) an amino acid other than valine at a position corresponding to amino acid residue 143 of SEQ ID NO: 1, (iii) or both (i) and (ii). Certain aspects of the present disclosure are directed to nucleic acid molecules encoding the HLA class II molecules, vectors comprising the nucleic acid molecule, cells comprising the same, and methods of use thereof.

The invention discloses a salicylic acid decarboxylase mutant and application of the salicylic acid decarboxylase mutant in degradation of salicylic acid. The mutant is obtained by carrying out site-specific modification on salicylic acid decarboxylase NahG, and specifically, valine at the 46th site, tyrosine at the 380th site and leucine at the 382nd site of an amino acid sequence shown in SEQ ID NO.2 are mutated into cysteine, phenylalanine and phenylalanine at the same time. The mutant shows remarkably improved catalytic efficiency, and salicylic acid can be efficiently and thoroughly decarboxylated and converted into catechol under mild conditions. The invention also provides a coding gene, a recombinant vector and an engineering bacterium of the mutant. The mutant not only can be used for efficient bioremediation of salicylic acid pollution, but also can effectively break through and accelerate a naphthalene catabolism pathway due to the characteristic of directionally generating catechol, and has important application value in the fields of environmental pollution abatement and biological catalysis.

The invention belongs to the technical field of enzyme mutants, and discloses a mutant of lycopene cyclase and application of the mutant, glutamic acid at the 321 site of wild type lycopene cyclase which is derived from arabidopsis and has an amino acid sequence as shown in SEQ ID NO.1 is mutated into lysine, phenylalanine at the 319 site of the wild type lycopene cyclase is mutated into leucine, cysteine at the 323 site of the wild type lycopene cyclase is mutated into alanine, and the mutant of the lycopene cyclase is obtained. 1, and the lycopene cyclase mutant with the amino acid sequence as shown in SEQ ID NO. 2 is obtained. BTS1, CrtB and CrtI are integrated into a saccharomyces cerevisiae BY4741 strain, and a chassis strain ZA1 for stably producing alpha-carotene precursor lycopene is constructed; mutant expression plasmids are constructed, positive clone strains are screened out, and the epsilon-cyclization ability of mutant enzymes is remarkably higher than the beta-cyclization ability; the method comprises the following steps: by taking lycopene as a substrate, constructing an expression vector lipid droplet surrounding protein PET10; gene PAH1, DGA1 and Cat2 related to TAG synthesis and perilipid droplet protein PET10 are constructed on an expression vector and converted into ZA1, and when lycopene is used as a substrate, the efficiency of catalytic production of alpha-carotene is improved.

The invention relates to the technical field of graded screening, in particular to a graded screening system based on staggered stacked metal ring films and a preparation method and application. An organic ligand and two metal complexes are subjected to interface coordination assembly under the action of silver ions, an ordered staggered stacked metal ring film is constructed, the structure and performance of the metal ring film are precisely regulated and controlled, the metal ring film has a definite molecular sieve component difference, and then precise grading screening of different molecules is achieved. The film has an obvious lattice structure, has good crystalline orderliness, and can ensure the stability and reliability of the screening process. The graded screening system based on the staggered stacked metal ring membranes has excellent interception performance on target molecules, and effective separation of TAC from glucan and leucine can be achieved. The two-stage membrane classification screening strategy can also be popularized to separation and purification of other substances, and good universality and industrial application prospects are achieved.

The invention relates to aspartate kinase for relieving feedback inhibition of L-threonine and application of aspartate kinase, and belongs to the field of enzyme engineering and metabolic engineering. The mutant is obtained by carrying out E253K and / or K507E mutation on the basis of wild type aspartate kinase as shown in SEQ ID NO.1, the enzyme activity of the mutant is not obviously changed under the condition that the concentration of L-threonine is 0-12 mmol / L, and the feedback inhibition effect of L-threonine on the mutant is relieved. The method can be widely applied to synthesis of essential amino acids including L-threonine, L-tryptophan, L-isoleucine, L-lysine, L-leucine, L-valine, L-methionine, L-phenylalanine and the like.

This invention belongs to the field of diagnostic testing technology. Addressing the problem that existing gestational diabetes screening methods may miss the optimal time for early intervention, leading to the failure to promptly detect and manage some potentially hyperglycemic pregnant women, increasing the risk of adverse maternal and fetal outcomes, this invention proposes a plasma metabolic biomarker for the early diagnosis or prediction of gestational diabetes and its application. This plasma metabolic biomarker is at least one of L-lysine, propargylglycine, N6-acetyl-L-lysine, cyclic leucine, and glycine-deoxycholic acid. The five plasma metabolic biomarkers provided by this invention can be applied to the early diagnosis or prediction of gestational diabetes, and are of great significance for the prevention or treatment of gestational diabetes.

An Fc-binding polypeptide with improved alkaline stability comprising a mutant of the Fc-binding domain of Staphylococcus protein A (SpA), said mutant being defined by SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 22, SEQ ID NO 51 or EQ ID NO 52, wherein at least the asparagine or serine residue at a position corresponding to position 11 in SEQ ID NO: 4-7 has been mutated to an amino acid selected from the group consisting of glutamic acid, lysine, tyrosine, threonine, phenylalanine, leucine, isoleucine, tryptophan, methionine, valine, alanine, histidine and arginine.

The present specification relates to a composition including a new amide-based compound derived from an amino acid structure such as valine, leucine, phenylalanine, proline, pipecolic acid, or the like, wherein the composition exhibits a skin anti-aging or skin reverse-aging effect by restoring the size and number of dendrites of aged melanin-producing cells to those of young cells. As a result, the composition may exhibit a skin brightening effect by inhibiting the amount of melanin produced in the melanin-producing cells.

The application provides a candidate drug for promoting embryo implantation efficiency of patients with uterine redox imbalance type RIF, and belongs to the technical field of embryo implantation. In order to solve the problem of how to find potential intervention drugs for the pathological mechanism of uterine redox imbalance type RIF, a five-step high-efficiency drug screening strategy based on an in-vitro implantation model of uterine redox imbalance type repeated embryo implantation failure is adopted to ensure the reliability and functional correlation of the screening results. The candidate drug screened by the five-step high-efficiency drug screening strategy includes any one of the following drugs: avobenzone, vasopressin, ethylenediaminetetraacetic acid dipotassium, larotrectinib sulfate, citicoline, opicapone, iclapa, L-leucine, fulvestrant, malic acid and lucotinib. Among these candidate drugs, avobenzone, vasopressin and ethylenediaminetetraacetic acid dipotassium are the best three drugs for promoting the implantation efficiency of patients with uterine redox imbalance type RIF.

This invention provides a ketolic acid reductase mutant and its application in constructing genetically engineered bacteria that produce high levels of D-pantothenic acid. To address the technical problem of low D-pantothenic acid yield in existing microbial fermentation, this invention utilizes semi-rational enzyme design to obtain a substrate-specific ketolic acid reductase mutant, which is then applied to construct genetically engineered bacteria that produce high levels of D-pantothenic acid. Furthermore, this invention employs CRISPR-Cas9 gene editing technology to construct genetically engineered bacteria that produce high levels of D-pantothenic acid using the aforementioned ketolic acid reductase mutant, increasing D-pantothenic acid production by approximately 12.04%. Compared to the starting strain, the accumulation of valine in the fermentation broth remained almost unchanged compared to the control, but the accumulation of the branched-chain amino acid isoleucine was lower, achieving substrate-specific modification of the ketolic acid reductase.

The invention discloses a generalized pustular psoriasis diagnosis marker based on metabonomics and application of the generalized pustular psoriasis diagnosis marker. The diagnostic marker is prepared from one or more of the following 35 compounds: pyruvic acid, alpha-ketoisovaleric acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, methane thiophosphoric acid, proline, uracil, tranexamic acid, 4-aminobutyric acid, threonine, scopoletin, dodecanol, N-methyl-L-leucine, L-cysteine-glycine and L-kynurenine. The feed additive is prepared from the following raw materials: 3-hydroxybenzoic acid, allantoin, delta-tocopherol, xylofuranose, glucose-1-phosphoric acid, pyrophosphate, taurine, L-asparagine, phthalic acid, 4-(dimethylamino) azobenzene, 5-tert-butyl-1h-indole-2, 3-dione, quinic acid, glucose, histidine, lysine, palmitic acid, 7-methylguanine, oleic acid and whale acid. The marker can be used for accurately distinguishing patients with generalized pustular psoriasis from healthy people.

The invention belongs to the field of in-vitro diagnostic reagents, and particularly relates to application of a reagent for detecting biomarkers in serum in preparation of a cerebral arterial thrombosis diagnostic kit. The invention determines that the concentrations of lactic acid, isoleucine, fumaric acid, ketoglutaric acid, hypoxanthine, tyrosine, histidine and inosine in serum of a cerebral arterial thrombosis (IS) patient are significantly related to major atherosclerosis (LAA) and minor artery occlusion (SAO), so that the concentrations of the biomarkers can be used as a basis for diagnosing IS and distinguishing LAA and SAO.

The present disclosure can improve the degree of soy protein proteolysis and the ability to produce valine, isoleucine, and leucine, which are branched-chain amino acids, as well as other amino acids, such as threonine, glycine, tyrosine, and lysine. Accordingly, the present disclosure can prevent sarcopenia and has antioxidant activity. Also, the present disclosure can maintain protein metabolic balance and relieve sarcopenia by muscle synthesis.The self-aggregation, hydrophobicity, and intestinal adhesion of a mixed strain is improved compared to a case where a single strain used for the mixed strain is used. Therefore, when the mixed strain of the present disclosure is ingested, the strain can remain for a long time in the intestine.

The present disclosure relates to bifunctional compounds that cause the degradation of LRRK2; pharmaceutical compositions comprising the compounds; and methods of treating disorders associated with LRRK2, including Parkinson's Disease.

This invention discloses a cyclic lipopeptide delivery system, comprising a cyclic lipopeptide carrier and nucleic acid; the head of the cyclic lipopeptide carrier is composed of heptapeptides R1R2R2R3R4R2R2 linked together by amide bonds to form a ring, and the hydrophobic tail of the cyclic lipopeptide carrier is composed of a fatty acid with a carbon chain length of 6-44 forming an ester bond with the hydroxyl group on the head amino acid R3, with the following general structural formula: where R1 is a basic amino acid, including one of histidine (His), lysine (Lys), or arginine (Arg); R2 is a hydrophobic amino acid, including one of leucine (Leu), isoleucine (Ile), or valine (Val); R3 is a hydrophilic amino acid, including one of tyrosine (Tyr), serine (Ser), or threonine (Thr); R4 is one of glutamate (Glu) or glutamine (Gln); n is an integer from 5 to 43; the cyclic lipopeptide carrier encapsulates the nucleic acid drug to form cyclic lipopeptide-nucleic acid nanoparticles.

The invention discloses a recombinant full-length human-derived III-type collagen as well as a preparation method and application of the recombinant full-length human-derived III-type collagen. The method comprises the following steps: replacing at least one corresponding rare codon of glycine, proline, arginine, leucine, isoleucine, valine and / or glutamic acid host bacteria in a Gly-Pro-X or Gly-X-Pro tripeptide structure coded by a wild full-length human III-type collagen gene sequence with a synonymous codon used by the host bacteria at high frequency; the translation efficiency in prokaryotic systems such as escherichia coli is obviously improved; the method comprises the following steps: designing 6-12 gene segments with overlapping sequences, splicing by adopting an overlapping extension PCR (Polymerase Chain Reaction) technology to obtain a full-length optimized gene, constructing the full-length optimized gene to an expression vector, and transforming the full-length optimized gene into host bacteria for induced expression; the expression product exists in the form of an inclusion body, and the natural conformation of the expression product is recovered through in-vitro renaturation; according to the method, high-efficiency expression and active preparation of the full-length human-derived III-type collagen in a prokaryotic system are realized.

The present invention relates to peptide conjugates that comprise a plant-derived oligopeptide capable of crossing the blood-brain barrier (BBB) and a therapeutic or diagnostic agent. The BBB-penetrating oligopeptide is an oligopeptide according to Formula I, Asp–R2–Gly–Leu–R5–R6–R7–Leu–Gly–R10–R11–R12, wherein R2 represents Arg, Lys, Cyt, D-Arg or Orn; R5 represents Phe, Arg, Lys, His, Trp, Tyr, D-Tyr, D-Phe, Orn, 4-aminophenylalanine or 3-phenylpropionate; R6 represents Pro, Leu, Glu or Lys; R7 represents Phe or Trp; R10, R11 and R12 each independently represent Lys, Arg or Orn; or an oligopeptide according to Formula II, Glu–R2'–R3'–Gly–R5'–R6'–Glu–R8'–R9'–R10'–Glu–R12'–Leu–Pro–Gly, wherein R2', R3', R8', R10' and R12' each independently represent Lys, Arg or Orn; R5' represents Phe, Ile, Arg, Lys, His, Trp, Tyr, D-Tyr, D-Phe, 4-aminophenylalanine, or 3-phenylpropionate; R6' represents Met, Leu, Ile, Asn, norleucin, D-norleucin, seleno- methionine or D / L-2-hydroxy-(4-methylseleno)butanoic acid; and R9' represents Leu or Ile. The conjugates comprising a BBB-penetrating oligopeptide compound and a therapeutic agent can be used in treatments for diseases of the central nervous system (CNS). Furthermore, conjugates with a BBB-penetrating oligopeptide compound and a diagnostic agent can be used in both in vivo and in vitro diagnostic methods.

The invention discloses a promoter mutant and an application of the promoter mutant in production of isoleucine. The invention provides a DNA molecule which is any one of the following: A1) a DNA molecule with a nucleotide sequence as shown in SEQ ID No.2; a2) is a variant which is obtained by substitution, deletion or addition of one or more nucleotides at other positions except the 66th nucleotide in the nucleotide sequence as shown in SEQ ID No.2, and the obtained DNA molecule has the same or enhanced promoter activity. Experiments prove that a series of promoter mutants with different strength and regulation characteristics are constructed to replace natural promoters, so that the transcriptional level of a target gene in a key period of fermentation is accurately improved, and the yield of the target gene is increased. The promoter engineering strategy provides a new direction for improving the production performance of industrial microorganisms by optimizing endogenous stress-resistant elements.

This invention belongs to the field of biomedical technology and provides a polypeptide with ATG8 protein binding activity, comprising the following structure: X1-X2-X3-X4-X5-X6-X7; wherein: X1, X2, and X3 are independently selected from glutamic acid or are absent; X4 is selected from tryptophan, phenylalanine, or leucine; X5 is valine; X6 is selected from leucine, isoleucine, or valine; and X7 is selected from valine, tryptophan, phenylalanine, or tyrosine. Compared with existing autophagy inhibitors, this polypeptide has the following superior pharmacokinetic potential and development flexibility in terms of target selection, binding strength, and mechanism of action: the short sequence not only reduces synthesis costs but also leaves more room for modification, which is expected to significantly improve the metabolic stability and drug-likeness potential of the polypeptide; it can serve as a highly efficient ATG8 targeting ligand and can be widely used in the construction of biochemical probes, screening of PPI competitive inhibitors, and the development of targeted delivery systems.