842 results about "Leucines" patented technology

The invention belongs to the technical field of biology, and relates to an escherichia coli engineering strain for producing L-isoleucine through a methyl malic acid way as well as a construction method and application of the escherichia coli engineering strain. According to the invention, Escherichia coli BW25113 is used as a chassis strain, and a methyl malic acid synthase high-activity mutant gene cimA3.7, an isopropyl malic acid isomerase gene GsleuCD, a 3-isopropyl malic acid dehydrogenase gene AfleuB and a leucine dehydrogenase gene Lsleudh are over-expressed; a methyl malic acid absorption protein gene is over-expressed, and a branched chain amino acid transport system is modified to improve the exosome of the L-isoleucine; all methyl malic acid pathway related genes are integrated to a genome of a chassis strain, and a plasmid-free L-isoleucine production strain is constructed; the copy number of a key gene on a genome is optimized, and the yield of the engineering strain L-isoleucine is increased by introducing a non-oxidative glycolysis approach. The yield of the L-isoleucine after the engineering strain is fermented for 34 hours in a fermentation tank is 56.6 g / L.

The invention provides a keto-alcohol acid reductoisomerase mutant and application of the keto-alcohol acid reductoisomerase mutant in construction of genetically engineered bacteria for high yield of D-pantothenic acid. In order to solve the technical problem that in the prior art, the yield of D-pantothenic acid synthesized through microbial fermentation is not high, semi-rational design of enzyme is adopted, and a keto-alcohol acid reductoisomerase mutant with substrate specificity is obtained and applied to construction of genetically engineered bacteria for high yield of D-pantothenic acid. According to the invention, a genetically engineered bacterium with high yield of D-pantothenic acid is constructed by utilizing the keto-alcohol acid reductoisomerase mutant through a CRISPR-Cas9 gene editing technology, so that the yield of D-pantothenic acid is increased by about 12.04%, and compared with an original strain, the valine accumulation amount in obtained fermentation liquor is almost unchanged compared with that of a control, and the yield of D-pantothenic acid is greatly improved. However, the accumulation of branched chain amino acid isoleucine is less, so that the modification of the substrate specificity of the keto-alcohol acid reductoisomerase is achieved.

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 gene engineering and enzyme engineering, in particular to an esterase mutant for degrading ethyl carbamate and application of the esterase mutant, the esterase mutant has an amino acid sequence as shown in SEQ ID NO.1 which is subjected to site mutation, the site mutation is any one or more site combined mutation of V129S, V161L or I229M, and the amino acid sequence of the esterase mutant is shown in SEQ ID NO.1. The V129S site mutation is that valine at the 129 site is mutated into serine, the V161L site mutation is that valine at the 161 site is mutated into leucine, and the I229M site mutation is that isoleucine at the 229 site is mutated into methionine. Mutation is carried out through a site-directed mutagenesis method, so that the amino acid sequence of the esterase mutant V129S / I229M is changed, the autoplasmic structure and function of eggs are changed, the esterase mutant V129S / I229M with the ethyl carbamate hydrolysis rate increased to 6.55 times in an acid environment is finally obtained, and the esterase mutant V129S / I229M has high industrial application value.

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 is directed to acetyl-leucine or a pharmaceutically acceptable salt thereof for use in improving cognitive function, mobility, or cognitive function and mobility in a subject, for example, in an elderly subject.

The present disclosure provides methods of treating a SYNGAP1-related disorder in a subject by administering a therapeutically effective amount of N-acetyl leucine.

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 relates to laccase as well as a mutant and application thereof, and belongs to the technical field of biology. The amino acid sequence of the laccase PnLac1 is as shown in SEQ ID NO. 2, and the nucleotide sequence of the laccase PnLac1 is as shown in SEQ ID NO. 1. The mutant is characterized in that aspartic acid at the 166th position of laccase PnLac1 is subjected to site-specific mutagenesis, histidine at the 348th position of laccase PnLac1 is subjected to site-specific mutagenesis, methionine at the 403th position of laccase PnLac1 is subjected to site-specific mutagenesis, or leucine at the 467th position of laccase PnLac1 is subjected to site-specific mutagenesis, amino acid sequences are shown as SEQ ID NO.4, SEQ ID NO.6, SEQ ID NO.8 and SEQ ID NO.10, and nucleotide sequences are shown as SEQ ID NO.3, SEQ ID NO.5, SEQ ID NO.7 and SEQ ID NO.9. The decoloring efficiency of the laccase PnLac1 on crystal violet reaches 5h, and the degradation rate reaches 75%. When the ABTS is used as a substrate, the enzyme activities of the laccase mutants H348F and L467M are respectively improved by 1.89 times and 1.65 times, and the ABTS has the potential of degrading stubborn substances; when guaiacol is used as a substrate, the enzyme activities of the laccase mutants D166A and M403F are respectively improved by 2.07 times and 3.72 times, and the guaiacol has a relatively high application prospect in the field of lignin.

The invention belongs to the technical field of gene engineering, and particularly relates to an RNA polymerase beta subunit mutant and application thereof. The RpoB mutant is obtained through a gene editing technology, after the 560th amino acid of the RpoB is changed into leucine from proline, the number of living cells during strain fermentation is greatly increased, the tolerance of the RpoB mutant in the later environment of a fermentation tank is improved, the RpoB mutant is applied to escherichia coli for producing human milk oligosaccharide, and finally the yield of the human milk oligosaccharide is greatly increased.

The invention relates to the technical field of biology, in particular to an L-amino acid synthesis system and application. According to the L-amino acid synthesis system and application provided by the embodiment of the invention, in the presence of coenzyme NAD < + >, isopropanol is catalyzed by isopropanol dehydrogenase to generate acetone, and NAD < + > is reduced into coenzyme NADH; in the presence of coenzyme NADH, the leucine dehydrogenase mutant utilizes NH3 generated by ammonia water volatilization to perform asymmetric reductive amination on a prochiral alpha-keto acid compound, the NADH is oxidized into NAD +, the catalytic efficiency of asymmetric reductive amination of the leucine dehydrogenase mutant on the prochiral alpha-keto acid compound is improved, the circulating speed of the coenzyme NADH and NAD + is increased, and the catalytic activity of the leucine dehydrogenase mutant on the prochiral alpha-keto acid compound is improved. The catalytic efficiency of asymmetric reductive amination of the leucine dehydrogenase is favorably improved.

The invention provides a keto-alcohol acid reductoisomerase mutant and application of the keto-alcohol acid reductoisomerase mutant in construction of genetically engineered bacteria for high yield of D-pantothenic acid. In order to solve the technical problem that in the prior art, the yield of D-pantothenic acid synthesized through microbial fermentation is not high, semi-rational design of enzyme is adopted, and a keto-alcohol acid reductoisomerase mutant with substrate specificity is obtained and applied to construction of genetically engineered bacteria for high yield of D-pantothenic acid. According to the invention, a genetically engineered bacterium with high yield of D-pantothenic acid is constructed by utilizing the keto-alcohol acid reductoisomerase mutant through a CRISPR-Cas9 gene editing technology, so that the yield of D-pantothenic acid is increased by about 12.04%, and compared with an original strain, the valine accumulation amount in obtained fermentation liquor is almost unchanged compared with that of a control, and the yield of D-pantothenic acid is greatly improved. However, the accumulation of branched chain amino acid isoleucine is less, so that the modification of the substrate specificity of the keto-alcohol acid reductoisomerase is achieved.

The invention relates to the technical field of biology, and discloses a carbonyl reductase mutant and application thereof in enzymatic synthesis of chiral alcohol. The amino acid sequence as shown in SEQ ID NO.2 is subjected to mutation that 36th lysine is mutated into any one of aspartic acid, threonine and valine, or / and 125th histidine is mutated into any one of lysine, serine and leucine, or 170th histidine is mutated into any one of lysine, cysteine and leucine. The carbonyl reductase mutants, especially single-site mutants Mut-T75K, Mut-T75D and Mut-E216M and a combined mutant Mut-T75K-E216M, with activity improved to different extents compared with that of a wild type are obtained, have excellent relative enzyme activity, thermal stability and substrate tolerance, have relatively high activity and stability for various chiral alcohols, and can be used for preparing the carbonyl reductase mutants. The catalyst has the advantages of high catalytic activity, high thermal stability, strong substrate tolerance, easiness in fermentation and the like.

The invention discloses a p-nitrophenyl ethyl esterase mutant with high enantioselectivity as well as a construction method and application of the p-nitrophenyl ethyl esterase mutant. The p-nitrophenyl ethyl esterase mutant is obtained by mutating an amino acid sequence of wild p-nitrophenyl ethyl esterase pnbA as shown in SEQ ID NO.1 according to one or a combination of more of the following modes: leucine at the 273rd site is mutated into aspartic acid, phenylalanine at the 314th site is mutated into histidine, and leucine at the 362nd site is mutated into arginine. The mutant pnbA-L273D / F314H / L362R provided by the invention shows optimal catalytic performance (E = 47.16) for racemization-acetic acid pinyl hydrate, the enantiomeric excess value of the mutant is 95.13%, the conversion rate of 1S, 5R-acetic acid pinyl hydrate is 90.42%, the enantioselectivity of the mutant is obviously higher than that of a wild type, and the mutant has great application potential in biological catalytic synthesis of monocyclic monoterpenoid chiral alcohols.

The invention discloses intestinal bacteria and serum metabolites which can be used as biomarkers of type 2 diabetes mellitus (prediabetes mellitus (PDM), new diagnosis diabetes mellitus (NDDM) and diabetes mellitus (P2DM) after medication) in different disease stages, and application of the intestinal bacteria and the serum metabolites. Aiming at type 2 diabetes mellitus, predictive markers including staphylococcus aureus, escherichia coli, klebsiella pneumoniae, branched chain amino acids (leucine, valine and isoleucine) and the like, especially staphylococcus aureus of which the genome contains acetolactate synthase (ALS), are efficiently screened out. The type 2 diabetes mellitus marker disclosed by the invention can be used for early warning the illness risk of type 2 diabetes mellitus and guiding the adjustment of an intestinal microbial environment; the method can be used for indicating the correlation between the intestinal microbial environment and the type 2 diabetes mellitus and is used for assisting diagnosis; and drug action target research, accurate medication, pathogenesis research and the like are realized.

The embodiment of the invention provides a fermentation method of L-leucine and L-isoleucine. According to the method, at least one L-leucine or L-isoleucine producing strain is used for fermentation culture; according to the method, relatively cheap molasses with rich carbon and nitrogen sources is selected as materials, corn steep liquor with more impurities is abandoned, and the molasses is converted into a nutrient substance containing more carbon and nitrogen sources capable of being utilized by strains through enzymolysis; in addition, in order to control the ratio of carbon and nitrogen sources in the fermentation liquor, a more accurate material supplementing process is selected, so that the fermentation requirements of strains can be guaranteed, and the situation that the liquid nitrogen source of the fermentation liquor is too high and too low can be effectively avoided, and the purposes of increasing the yield and the sugar acid conversion rate and reducing heteroacid byproducts are achieved.

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 discloses a high-yield delta-tocotrienol genetically engineered bacterium and application thereof, and belongs to the technical field of gene recombination. The invention discloses a genetically engineered bacterium for high yield of delta-tocotrienols, which is characterized in that yarrowia lipolytica ATCC MYA-2613 is used as an original strain, and a ku70 gene is knocked out; the gene is used for expressing and coding 4-hydroxyphenylpyruvate dioxygenase, the gene is used for coding uromelanic acid phytate transferase and the gene is used for coding tocopherol cyclase; intensifying a shikimic acid pathway; a mevalonic acid pathway is strengthened; an isopentenol path is introduced; carrying out protein fusion on the HPD and the HPT; truncating a signal peptide of a gene encoding a tocopherol cyclase and back-filling a leucine defect. The genetically engineered bacterium constructed by the invention has industrial stability, can be amplified by more than 10 times in a 2L fermentation tank level compared with a shake flask level, can produce 616.45 mg / L of delta-tocotrienol after being cultured for 240 hours, and has industrial application prospects.

The invention discloses a polypeptide with a whitening effect and a preparation method and application thereof.The polypeptide is obtained from hydrolyzed protein of babylonia areolata, the amino acid sequence of the polypeptide is cysteine-arginine-proline-threonine-cysteine-serine-arginine-leucine-alanine-cysteine, and the amino acid sequence of the polypeptide is cysteine-arginine-proline-threonine-cysteine-serine-arginine-leucine-alanine. The compound can obviously inhibit the generation of melanin in cells and the activity of tyrosinase in vitro, has the characteristics of low toxicity, low irritation, good stability, safety and high efficiency, and can be applied to whitening cosmetics.

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.

Provided are methods for synthesizing compounds having activity against Leucine- rich repeat kinase 2 (LRRK2), as well as intermediates generated during said methods.

The invention discloses a yak bone collagen peptide for improving osteoporosis and preparation and application thereof, and relates to the field of biological medicine, the yak bone collagen peptide comprises collagen peptide with the molecular weight of 500-2000 Daltons, contains a glycine-proline-hydroxyproline tripeptide core structure, can promote osteoblast differentiation and inhibit osteoclast activity, and can be used for treating osteoporosis. The amino acid sequence of the collagen peptide is any one of the following sequences: glycine-proline-hydroxyproline-glycine-glutamic acid-arginine, and the amino acid sequence of the collagen peptide is any one of the following sequences: glycine-proline-hydroxyproline-glycine-glutamic acid-arginine; and the amino acid is glycine, proline, hydroxyproline, serine, leucine and alanine. The yak bone collagen peptide has a unique glycine-proline-hydroxyproline tripeptide structure, the molecular weight is controlled within the range of 500-2000 Daltons, the structure can promote osteoblast differentiation and inhibit osteoclast activity at the same time, and the problem that a traditional osteoporosis treatment medicine is single in function is solved.

The present application relates to a pyridoxal kinase mutant, a recombinant expression vector and a microbial cell and their applications, and belongs to the technical field of biological catalysis. In order to solve the problem of low product concentration in existing enzyme catalysis, a pyridoxal kinase mutant is provided, the amino acid sequence is selected from the amino acid sequence shown in SEQ ID NO. 1, the lysine at position 229 is mutated to alanine, phenylalanine, methionine, arginine, threonine, histidine, serine, tyrosine, valine, leucine, isoleucine, proline, asparagine, aspartic acid or glutamic acid; the pyridoxal kinase mutant is used for catalyzing pyridoxal to synthesize pyridoxal phosphate, and a recombinant expression vector and a microbial cell can be further formed. The present application has good enzyme activity, high product conversion rate, high concentration of pyridoxal phosphate obtained, and the concentration of the product catalyzed by the wild-type pyridoxal kinase to phosphorylate pyridoxal is obviously improved.

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 belongs to the technical field of gestational diabetes diagnosis marker screening, and particularly relates to a biomarker for predicting or diagnosing gestational diabetes and application of the biomarker. The invention discloses a biomarker for predicting or diagnosing gestational diabetes mellitus, the biomarker is selected from one or more of hypoxanthine, cortisol, dihydrotachysterol and cycloleucine, and more preferably, the biomarker comprises hypoxanthine, cortisol, dihydrotachysterol, (3R, 4R)-D-ketolactone, creatine, cycloleucine and L-hydroorotic acid. The seven biomarkers disclosed by the invention can predict or diagnose gestational diabetes mellitus independently or jointly through plasma detection at the early pregnancy stage, effectively improve the early diagnosis rate of gestational diabetes mellitus and improve disease prognosis, and have clinical use and popularization values.

The invention discloses a leucine dehydrogenase mutant and application thereof.The mutant is obtained by replacing any one or more amino acid residues in the 36th site, the 59th site and the 109th site on the basis of a wild leucine dehydrogenase amino acid sequence, compared with the wild leucine dehydrogenase amino acid sequence, the enzyme activity of the mutant is improved by 5 times or above, the LeuDH mutant is guided into host bacteria, and the activity of the LeuDH mutant is improved by 5 times or above. The obtained recombinant bacterium is used for fermentation production of L-isoleucine, the yield of L-isoleucine reaches 30 g / L or above, compared with a wild type, the yield is remarkably improved, and powerful support is provided for fermentation production of an L-isoleucine product.

The invention relates to a blood protein peptide for promoting hair follicle reconstruction and application thereof, and belongs to the technical field of bioactive peptides. The blood protein peptide disclosed by the invention is selected from one or more of an MLL peptide fragment and a WDL peptide fragment; the amino acid sequence of the MLL peptide fragment is as follows: methionine-leucine-leucine; the amino acid sequence of the WDL peptide fragment is as follows: tryptophan-aspartic acid-leucine. The invention also provides a preparation method of the blood protein peptide and application of the blood protein peptide in hair follicle reconstruction. The blood protein peptide prepared by the technical scheme of the invention can obviously improve local blood supply around hair follicles, and has a wide application prospect in the field of treatment of alopecia.