8 results about "Lactate dehydrogenase" patented technology

The invention discloses a high-stability hydroxysteroid dehydrogenase mutant, a co-immobilized enzyme construction method and application. According to the invention, a site-directed mutant library is constructed based on computer-aided design, and mutants with significantly improved thermal stability and greatly improved catalytic efficiency compared with wild type mutants are obtained through screening; meanwhile, a co-immobilized enzyme construction method based on electrostatic adsorption and chemical crosslinking is established, the hydroxysteroid dehydrogenase mutant and lactic dehydrogenase are co-immobilized, the co-immobilized enzyme can still keep high activity under high substrate concentration, and the conversion rate is still maintained to be 90% or above after 30 batches of co-immobilized enzyme are repeatedly used. And an important foundation is laid for industrial application of the hydroxysteroid dehydrogenase.

The present invention relates to ssDNA aptamers speciically binding to Plasmodium lactate dehydrogenase (LDH). The invention provides ssDNA aptamers having the nucleotide sequence of SEQ ID NO: 1 or SEQ ID NO: 2, which are capable of binding LDH from at least Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae. The aptamers enable in vitro detection of malaria independently of the infecting Plasmodium species and may be used in diagnostic compositions, kits, and biosensor-based detection systems.

This invention belongs to the fields of fermentation and genetic engineering technology, and provides a high-yield hexanoic acid-producing engineered *Escherichia coli* strain, its construction method, and its applications. This engineered strain is *Escherichia coli*... E. coli w3110 was the starting strain, overexpressing the acetyl-CoA transferase gene. act and β-ketothiolase gene bktB Overexpression of trans-enoyl-CoA reductase gene ter 3-Hydroxybutyryl-CoA dehydrogenase gene hbd, and 3-hydroxybutyryl coenzyme A dehydratase gene crt Or, simultaneously not expressing the pyruvate formate lyase gene. pflB or lactate dehydrogenase gene ldhA This engineered bacteria can convert glucose into hexanoic acid, a high-value product, with a yield of 4.968 g / L after 18 hours of fermentation. It adopts aerobic fermentation, resulting in rapid cell growth, a short fermentation cycle, and a high acid production rate. The fermentation process is simple, easy to control, and has low production costs, which is conducive to its promotion and application in industrial production.

This invention discloses a recombinant *E. coli* strain for producing phenyllactic acid, a lactate dehydrogenase mutant, a whole-cell catalytic method for preparing phenyllactic acid, and the application of the aforementioned recombinant *E. coli* strain or lactate dehydrogenase mutant in the catalytic preparation of phenylpyruvic acid from phenyllactic acid. This invention significantly improves catalytic efficiency by modifying the 52nd amino acid of lactate dehydrogenase through site-directed mutagenesis. After mutating glutamine (Q) to valine (V) at position 52 of the *Lactobacillus mucosa* lactate dehydrogenase, the catalytic efficiency is significantly improved even at low cell density (OD). 600 =15) and substrate 15 g / L conditions, almost complete conversion was achieved; and combined with high-density catalysis and surface display optimization, the yield of phenyl lactic acid was increased while the downstream separation and purification costs were significantly reduced, greatly enhancing the potential for industrial production.

The invention relates to the field of food processing, in particular to a preparation method of whole-plant fried ginseng and application of the whole-plant fried ginseng in preparation of drugs or food for resisting oxidation and relieving fatigue. The method comprises the following steps: fresh ginseng is taken and cleaned, rhizome, main roots and fibrous roots are separated, the main roots are cut into slices or segments, the rhizome, the slice-shaped main roots or the segment-shaped main roots and the fibrous roots are respectively placed in oil to be fried, and when the rhizome, the slice-shaped main roots or the segment-shaped main roots and the fibrous roots are golden yellow, the rhizome, the main roots and the fibrous roots are fished out, drained off oil and cooled. The antioxidant activity of the fried ginseng slices and segments is improved. Compared with fresh ginseng, the deep-fried ginseng slices and segments can significantly prolong exhaustive swimming time of load-bearing mice, significantly improve liver / muscle glycogen, lactic dehydrogenase content and superoxide dismutase activity, reduce lactic acid, urea nitrogen and malondialdehyde content, and have a significant anti-fatigue effect. According to the method, dryness of fresh ginseng can be removed, the eating fragrance can be improved, the fried ginseng product is instant and convenient to eat, and the fried ginseng product is matched with barbecue kebabs and stewed together with livestock and poultry meat, so that the fried ginseng product is delicious and health-care.

The invention belongs to the field of gene engineering, and discloses clostridium tyrobutyricum for producing butyl butyrate by jointly utilizing glucose and xylose as well as a construction method and application of the clostridium tyrobutyricum. The strain has the following characteristics: a restriction enzyme rease gene is knocked out, a lactic dehydrogenase ldh2 gene, a lactic dehydrogenase ldh3 gene and a lactic dehydrogenase ldh1 gene are knocked out, an HPr kinase / phosphorylase hprK gene is knocked out, an aldol dehydrogenase adhE2 gene is knocked in at the site, a xylose transcription inhibition factor xylR gene is knocked out, and an aldol dehydrogenase adhE2 gene is knocked in at the site; a butyryl-CoA / acetic acid CoA transferase cat1 gene is knocked out, an aldehyde alcohol dehydrogenase adhE2 gene is knocked into the site, and alcohol acyltransferase VAAT and heat shock protease GroESL are overexpressed. The strain is obtained by a gene editing method, and can utilize glucose and xylose in lignocellulose hydrolysate to produce butyl butyrate at high yield.

This invention discloses an engineered strain for producing monascin, its construction method, and its applications, belonging to the field of microbial engineering technology. The starting strain was treated as follows: (1) FAD oxidoreductase was knocked out. MrpigF Gene; (2) Overexpression of enoyl reductase MrpigH Genes; (3) Overexpression of transcription factors pig Genes; (4) Knockout of lactate dehydrogenase ldhA Genes. This invention employs a metabolic engineering strategy of increasing precursor supply, blocking competing pathways, and enhancing the target product synthesis pathway to target key enzyme genes in the upstream pathway of red yeast rice pigment biosynthesis. ldhA Key enzyme genes in downstream pathways MrpigH and MrpigF and red yeast rice pigment gene cluster regulatory genes pig Knockout or overexpression was performed to improve the biosynthetic efficiency of monaxiocin and to construct genetically engineered strains that produce monaxiocin efficiently.

Provided is a method for producing pyruvic acid by using non-NADP-dependent lactate dehydrogenase. The method comprises: S1: constructing a recombinant Escherichia coli strain expressing lactate dehydrogenase; S2: obtaining lactate dehydrogenase-producing whole cells from the recombinant Escherichia coli strain expressing lactate dehydrogenase; and S3: obtaining pyruvic acid by means of a whole-cell catalytic reaction of the lactate dehydrogenase-producing whole cells. By means of constructing a genetically engineered Escherichia coli strain, the addition of NAD +／NADP + as electron acceptors is not required during the conversion to produce the pyruvic acid. Furthermore, the method achieves a higher pyruvic acid yield, simpler operation and reduced raw material consumption. The selected substrate, sodium lactate, is inexpensive and readily available, and the production process for the pyruvic acid is simple. The method has good prospects for industrial application.