758 results about "Alanine" 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 invention relates to the technical field of biological catalysis, and discloses an M88A mutant enzyme for preparing rebaudioside I. The enzyme is obtained by the following mutations generated by UGT76G1: M88A: methionine of the 88th amino acid sequence of UGT76G1 is mutated into alanine; the key conversion rate of RI is greatly increased from 7% to 85% (increased by more than 12 times), and the utilization rate and economical efficiency of raw materials are remarkably improved; the method can be perfectly reproduced under any test scale (10mL, 100mL and 5L), the conversion rate is always anchored to be more than 85%, and incomparable stability and amplification potential are shown.

The invention provides a method for detecting free amino acids in camellia oleosa seed oil, and establishes a method for detecting the free amino acids in the camellia oleosa seed oil based on ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS / MS), which comprises the following steps: pre-treating various amino acids in the camellia oleosa seed oil by using a non-derivation method; the problems of complicated operation, impurity interference and the like caused by derivatization are avoided, the extraction solvent is environment-friendly and economical, the extraction efficiency is high, and the pretreatment time is greatly shortened; then selecting a proper chromatographic column and a mobile phase, separating a plurality of free amino acids under the condition of not introducing excessive derivatization agents and ion pair reagents, and controlling the collection time to be 12 minutes. The method for detecting the free amino acids in the camellia oleosa seed oil has the characteristics of no need of derivatization treatment, simplicity and convenience in operation, high detection efficiency and good sensitivity and accuracy, and can effectively separate and detect 14 free amino acids such as alanine, phenylalanine and aspartic acid in the camellia oleosa seed oil.

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 relates to the field of plant molecular biology and forest genetic engineering, and particularly provides a PagRAP2.3 protein point mutant and application thereof in drought resistance of poplar. The mutant PagRAP2.3 MA is obtained by mutating methionine at the first site and cysteine at the second site of a wild type PagRAP2.3 protein into methionine and alanine. The invention further discloses a preparation method of the mutant PagRAP2.3. An expression vector containing the PagRAP2.3 MA gene is constructed, poplar 84K is transformed through an agrobacterium-mediated method, and a transgenic line with stable expression is obtained. Functional verification results show that overexpression of PagRAP2.3 MA can significantly increase the plant height of the poplar and promote plant growth, but the sensitivity to moisture is enhanced under drought stress. The mutant can be used for regulating and controlling the growth and development of forest trees and evaluating the drought resistance, and has a forestry breeding application prospect.

The invention belongs to the technical field of biological medicine, and particularly relates to application of phenylalanine in evaluating Kawasaki disease and treating effect thereof and application of a phenylalanine inhibitor in treating Kawasaki disease. According to serum non-targeted metabonomics analysis and verification of KD children and IVIG treated KD children, phenylalanine is highly expressed in KD children, and phenylalanine is remarkably reduced after IVIG treatment of KD and tends to healthy children. The phenylalanine can be used as a serological marker for evaluating the Kawasaki disease treatment effect and diagnosing IVIG second-line treatment, and is high in specificity and sensitivity. After the phenylalanine inhibitor is administered to a KD model mouse, the content of phenylalanine in serum is remarkably reduced and is consistent with the trend in serum of the KD mouse treated by IVIG, myrica tongues are remarkably relieved, arterial dilatation is slowed down, and expression of inflammatory factors is reduced. The phenylalanine inhibitor has the effects of treating Kawasaki disease, improving myrica rubra tongue and slowing down arterial dilatation.

The invention relates to the technical field of microorganisms, and particularly discloses a PhPepD mutant and application of the PhPepD mutant in fermentation production of L-carnosine. According to the invention, a new PhPepD mutant is screened by means of construction of a mutation library from PepD of different sources and error-prone PCR, site-directed saturation mutation and the like, the amino acid sequence of the PhPepD mutant is shown as SEQ ID NO: 18, and compared with wild type PhPepD protein, the PhPepD mutant has N158D / I176F / E393Q mutation. By using the mutant, a microorganism with increased L-carnosine yield can be obtained, and in recombinant microorganisms capable of producing carnosine without adding beta-alanine, the mutant also shows an effect of increasing the L-carnosine yield, and a new effective method is provided for industrial large-scale production of L-carnosine.

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.

According to the scheme, the invention provides the recombinant macrolide enzyme as well as the preparation method and the application thereof, the amino acid sequence of the recombinant macrolide enzyme is as shown in SEQ ID NO.1, and the recombinant macrolide enzyme is derived from an EreC esterase family of enterobacter hormaechei and is obtained through site-specific mutagenesis; the mutation sites are as follows: glutamic acid at the 44th site is mutated into asparagine, tyrosine at the 55th site is mutated into proline, proline at the 76th site is mutated into arginine, phenylalanine at the 153rd site is mutated into alanine, and serine at the 219th site is mutated into glutamic acid. The method is expected to remove macrolide antibiotic pollution, and has good economic benefits and practical values.

The invention discloses an application of beta-alanine in preparation of a medicine for treating pulmonary arterial hypertension. In-vivo and in-vitro pharmacological experiments prove that beta-alanine can inhibit lactic acid-mediated histone milk acylation modification and hypoxia-induced phenotypic transformation of PASMCs (Polyaspartic Sulfonate Molecules); the hemodynamics and pulmonary artery vascular remodeling of the PAH mouse are improved. The beta-alanine can inhibit phenotypic transformation of PASMCs and reverse pulmonary artery vascular remodeling which is a key pathological change in the pulmonary hypertension generation process, has huge potential in treatment of pulmonary hypertension, and has good application prospects and high clinical application value.

The invention discloses application of copper-amino acid nano enzyme in preparation of anti-inflammatory drugs, and relates to the technical field of biomedical new materials, amino acids comprise glycine, arginine, histidine, threonine, phenylalanine and cysteine; the ratio of the amino acid to the copper ions is 1: (0.5-5), and the synthesis temperature of the copper-cysteine nano enzyme is 25-125 DEG C. The copper-amino acid nano-enzyme library established by the invention has efficient hydroxyl free radical, superoxide free radical and hydrogen peroxide scavenging activity; wherein the copper-cysteine nano-enzyme shows the highest enzymatic activity, and shows low toxicity and good biocompatibility in both the cell level and the animal level; meanwhile, the copper-cysteine nano-enzyme also shows anti-inflammatory activity and anti-oxidative stress activity, can remarkably improve cell inflammation and body inflammation, relieves and treats dextran sodium sulfate induced mouse ulcerative colitis, and can be further applied to preparation of drugs for treating inflammatory bowel diseases.

The invention provides a feed premix for improving chicken quality. The fresh-keeping agent is prepared from the following components in percentage by weight: 5%-15% of a flavor enhancing component, 10%-25% of a tenderness improving component, 3%-10% of an antioxidant fresh-keeping component, 2%-3% of a function enhancing component and the balance of a carrier and a diluent, the function strengthening component is prepared from beta-alanine embedded citronella essential oil and konjac glucomannan zymolyte; the flavor enhancing component comprises a rosemary extract, a yeast culture and curcumin in a mass ratio of (2-4): (1-3): 1; the tenderness improving component comprises conjugated linoleic acid, L-carnitine modified by glutamine transaminase and betaine in a mass ratio of (3-5): (2-4): 1; the antioxidant fresh-keeping component is vitamin E and tea polyphenol in a mass ratio of (1-2): 1. Through multi-component synergism and functional targeting optimization, a three-dimensional quality improvement system with enhanced flavor, improved tenderness, oxidation resistance and fresh keeping is constructed, so that the chicken quality is comprehensively upgraded.

The invention discloses an LbCas12a protein mutant as well as a preparation method and application thereof, the LbCas12a protein mutant is obtained by performing K390A or K945A mutation on a wild type LbCas12a protein, and the amino acid sequence of the wild type LbCas12a protein is as shown in SEQ ID NO. 1. According to the present invention, the LbCas12a protein is subjected to directional modification, the alanine mutation occurs at the K390 / K945 site, the LbCas12a-K390A protein mutant and the LbCas12a-K945A protein mutant are prepared, the protein mutants obtained based on the method provide a series of significant advantages in function, and the solid foundation is laid for the application of the protein mutants in multiple fields. Through Michaelis-Menten kinetic analysis, it is observed that when the LbCas12a-K390A / K945A protein mutant prepared through the method and the wild type LbCas12a protein target the same dsDNA target, the catalytic efficiency of the LbCas12a-K390A / K945A protein mutant is 42.1 times that of the wild type LbCas12a, and the catalytic efficiency of the LbCas12a-K390A / K945A protein mutant is 707.9 times that of the wild type LbCas12a, and the catalytic efficiency of the LbCas12a-K390A / K945A protein mutant is 707.9 times that of the wild type LbCas12a. The results show that K390 and K945 are mutated into alanine, so that the affinity of the LbCas12a protein to a substrate can be increased to a certain extent, and the LbCas12a protein has higher trans-cleavage activity.

The invention relates to PYY analogues having alanine at position 4, lysine at position 7, QRY as the C-terminal end and a half-life extending group. The analogues of the invention are soluble around pH 6 and 7. The invention also relates to pharmaceutical compositions comprising such PYY analogues, and to the medical use of the analogues.

The application discloses an Escherichia coli probiotic with high beta-alanine yield and application thereof, and the recombinant genetically engineered bacterium takes a wild-type Escherichia coli probiotic as a starting strain and is subjected to one or more gene edits, including Trc promoter strengthening of a panD gene, an aspC gene, an sdhC gene and a ppc gene, overexpression of a panD gene from Bacillus subtilis, an aspB gene from Corynebacterium glutamicum, an aspA gene and a pyc gene from Corynebacterium glutamicum on a plasmid pTrc99a, and knockout of a cycA gene. 600 Compared with an existing reported Escherichia coli probiotic beta-alanine production strain, the OD of the recombinant genetically engineered bacterium is 4.4 times that of the existing reported strain, and the beta-alanine yield is 6 times that of the existing reported strain, so that the recombinant genetically engineered bacterium has great industrial application potential.

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 relates to the technical field of preparation of cured beef, and discloses low-salt cured beef which comprises main materials and auxiliary materials in parts by mass as preparation raw materials, the main materials comprise fresh yellow cattle meat and compound salt, and the auxiliary materials comprise tea polyphenol, alanine, calcium gluconate and a kelp powder aqueous extract. The formula comprises 100 parts of fresh yellow cattle meat, 5 parts of compound salt, 0.1 part of tea polyphenol, 0.2 part of alanine, 0.5 part of calcium gluconate and 1 part of kelp powder aqueous extract. The method comprises the following steps: putting cleaned beef strips into a microwave oven, mixing 5% of compound salt with tea polyphenol, anthocyanin, rosemary extract, alanine and calcium gluconate in order to improve the pickling efficiency, adding 50 parts of clear water, and uniformly stirring to prepare a pickling solution; and cooling the fried cured beef to room temperature, packaging with a vacuum packaging bag, and carrying out ultrahigh pressure treatment (300MPa, 5 minutes) to replace irradiation, prolong the shelf life and retain the flavor, so that the method has the advantages of traditional flavor, prolonged shelf life, simple production process and the like.

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 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.

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 invention discloses a preparation method of engineered bacteria for releasing CO gas under initiation of ultrasonic waves to kill tumor cells, and relates to a preparation method of CO carrier engineered bacteria. The invention aims to solve the problems that the existing CO carrier material is low in delivery efficiency, the CO is difficult to release efficiently and controllably in space and time at the same time, and the existing metal CO carrier material is high in toxicity. Meanwhile, the problems that the penetrating power of light waves to biological tissues is limited, and the CO release efficiency is limited due to a tumor hypoxic microenvironment are solved. The preparation method comprises the following steps: 1, modifying the surface of escherichia coli with 3-hydroxyflavone-D-alanine; and 2, continuously modifying the surface of the escherichia coli with CaO2 (at) polymyxin B. The method is used for preparing the engineered bacteria for releasing the CO gas through ultrasonic initiation to kill the tumor cells.

The purpose of the present invention is to provide a novel beer-flavor fermented alcoholic beverage which has a reduced sugar concentration and a good balance between taste strength and aftertaste. The present invention provides a beer-taste fermented alcoholic beverage having a saccharide concentration of 2.5 g / 100 mL or less, the beer-taste fermented alcoholic beverage having a glycine concentration of 5.5 mg / L or more, an alanine concentration of 4.4 mg / L or more, and a total concentration of glycine and alanine of 10 mg / L or more and 180 mg / L or less.

The invention relates to the technical field of pharmaceutical analysis, and particularly discloses a high performance liquid chromatography-mass spectrometry tandem method (HPLC-MS / MS) for detecting a genotoxic impurity L-alanine isopropyl ester in an emtricitabine-propofol tenofovir tablet. By optimizing chromatographic column selection, a mobile phase gradient elution procedure and mass spectrometric detection parameters, the method realizes exclusive, sensitive and accurate detection of the L-isopropyl alanine. The methodological verification result shows that the detection limit is 1.00 ng / mL, the quantification limit is 2.00 ng / mL, the linear range is 2.00-100.00 ng / mL (the correlation coefficient r is equal to 0.9994), the recovery rate is stabilized between 92% and 98%, and the precision and repeatability are good. The detection method has the advantages of high sensitivity and strong selectivity, is suitable for quality control of emtricitabine propofol tenofovir tablets, meets the control requirements of ICH M7 guide on genotoxic impurities, and has good practicability and popularization value.

The application relates to a synthesis method of an anti-freezing glycopeptide polypeptide and belongs to the technical field of polypeptide drug synthesis. The method comprises the following steps: 2-CL-Resin is used as a carrier resin, under the condition of adding an activating agent, the carrier resin and alanine are coupled to obtain Fmoc-Ala-2-CL-Resin; according to the amino acid sequence of the anti-freezing glycopeptide, other amino acids are sequentially coupled through a solid-phase synthesis method; after a protecting group is removed and the carrier resin is cleaved, the anti-freezing glycopeptide crude peptide is obtained; and after purification, salt conversion and freeze-drying, the anti-freezing glycopeptide polypeptide is obtained. The method has the advantages of short synthesis period, low cost, easy post-treatment, few by-products, high product yield, facilitation of large-scale production of the anti-freezing glycopeptide, and considerable economic applicative value and wide application prospect.

The present patent application concerns a hydrogel formulation for cleaning stone surfaces comprising: a first chelating agent consisting of citric acid, a second chelating agent selected from the group consisting of Tetrasodium glutamate diacetate, Trisodium dicarboxymethyl alaninate and combinations of the above, a supporting agent consisting of xanthan gum, at least one co-densifier, at least one surfactant, at least one antibacterial and / or anti-mould, water, wherein the weight ratio of the sum of the first chelating agent and the second chelating agent to the xanthan gum is comprised from 1:0.7 to 1:1.6.

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 invention discloses an application of a biomarker in evaluating the risk of progressing from autoimmune hepatitis to cirrhosis. The biomarker comprises immune globulin G, and / or an antinuclear antibody, and / or aspartate aminotransferase and alanine aminotransferase. Independent predictive factor indexes of the liver cirrhosis risk of an autoimmune hepatitis patient in the biomarker are as follows: an antinuclear antibody ANA index: log2ANA is greater than or equal to 1.62; the AAR index of the ratio of aspartate aminotransferase to alanine aminotransferase is as follows: AAR is greater than or equal to 1.62; the immune globulin G, namely the IgG index, is greater than or equal to 30.3 g / L. The problems that in the prior art, an AIH risk model does not take cirrhosis as the outcome, visual presentation is lacked, prediction efficiency is insufficient, and clinical early-stage accurate risk layering and diagnosis and treatment decision requirements are difficult to meet are solved.

The application relates to the technical field of beef cattle breeding, and particularly discloses a compound preparation for promoting the feed intake, daily weight gain and improving the meat quality of beef cattle and application thereof, which is prepared from the following components in percentage by volume: 40% of micro-ecological preparation, 30% of hawthorn, 10% of medicated leaven, 10% of malt, 5% of areca nut and 5% of dried tangerine or orange peel; the compound preparation is prepared from microorganisms and multiple natural Chinese herbal medicines in a specific and scientific matching ratio; experiments prove that the compound preparation can increase the feed intake of beef cattle by 11.33%, increase the daily weight gain by 16.16%, and significantly shorten the breeding cycle; meanwhile, the contents of aspartic acid, threonine, glutamic acid, alanine, valine, isoleucine, leucine, tyrosine, phenylalanine, lysine, arginine and proline in the muscle are significantly increased, the nutritional quality and flavor taste of beef are effectively improved, the preparation is natural, residue-free and side-effect-free, the preparation method is simple, the cost is low, and the preparation has extremely high practical value and popularization prospect.

The application discloses a beta-1,4-xylanase mutant and a construction method thereof, and comprises the following steps: constructing a beta-1,4-xylanase recombinant expression vector; introducing the recombinant vector pNZ8048-P5-XynA into a competent lactococcus lactis by using an electrotransformation technology to construct a wild-type expression vector; on the basis, designing and constructing a multi-site mutant recombinant plasmid by using a site-directed mutation method, wherein the eighth asparagine (Asn) of the beta-1,4-xylanase is mutated into tyrosine (Tyr), the 22nd serine (Ser) is mutated into proline (Pro), and the 59th alanine (Ala) is mutated into lysine (Lys); introducing the multi-site mutant recombinant plasmid into the competent lactococcus lactis to construct a heterologous expression strain of the mutant beta-1,4-xylanase (Mut-1); and stably obtaining the mutant xylanase beta-1,4-xylanase (Mut-1) with high activity by using a metal affinity chromatography (Ni 2+ ) method. The specific enzyme activity of the mutant reaches 1929.30±5.36 U / mg, and the optimal temperature is increased by 15 DEG C compared with that of the wild type.