30 results about "Levanase activity" patented technology

Isolated polynucleotides encoding polypeptides having the activity of enzymes in the mevalonate pathway are provided. These sequences are useful for recombinantly producing isoprenoid compounds, such as carotenoids, in particular zeaxanthin. Expression vectors, cultured cells, and methods of making isoprenoid compounds are also provided.

The invention discloses an application of a novel fructosidase coding gene. Fructosidase has the amino acid sequence shown as SEQ.ID NO:1 in a sequence table. The coding gene has the nucleotide sequence shown as SEQ.ID NO:2 in the sequence table. The fructosidase originates from Lactobacillus plantarum, compared with fructosidase originating from other sources, the enzyme has the enzymatic activity of decomposing FOS (fructooligosaccharides) and freeing fructose radicals from the FOS as well as the inulinase activity and levanase activity; lactic acid bacteria without the capability of utilizing the FOS can have the capability of utilizing the FOS when the enzyme is heterogeneously expressed in the other lactic acid bacteria.

The invention relates to a method for screening and testing activity of a lysine propionylation removal enzyme and a butyrylation removal enzyme. The basis thought of the method is that: lysine propionylation or butyrylation modification degree of a substrate can be reflected by the sensitivity of the substrate to the catalysis removal enzyme. The method comprises the following steps of: a, lysine propionylation substrate polypeptide marked with releasable signal substances; b, the lysine propionylation removal enzyme; and c, a detection method for distinguishing the modification lysine propionylation polypeptide from corresponding non-modification polypeptide. The method can be used for screening modification removal enzymes and testing the activity of the enzymes, and also can screen substrates influencing the activity of the enzymes to be further used in quick diagnosis of several diseases.

The invention relates to thermophilic long-chain alkyl aldehyde dehydrogenase in an n-alkane end degradation process of thermophilic denitrified bacillus and a crystal structure thereof. A molecular clone method is utilized, so that a target gene is cloned into escherichia coli (E. coli) so as to be heterologously expressed. A purified product of aldehyde dehydrogenase is obtained through a protein purification method. A crystal of the aldehyde dehydrogenase, which is suitable for diffraction, is obtained through a hanging droplet crystallization method. The crystal structure of the aldehyde dehydrogenase is analyzed by utilizing an X-ray diffraction method. The results show that the aldehyde dehydrogenase contains a characteristic ALDH fold which is formed by three structural domains. Site-specific mutagenesis is carried out on conserved residues on an enzyme activity part, and the influence of the conserved residues on enzyme activity is proved through wild type of the enzyme and enzyme activity experiment of the mutant thereof. The results can comprehensively reflect space conformation of the enzyme, and provide theoretical guidance for further researching relation between structures and functions of the aldehyde dehydrogenase, and improving the degradation activity of the enzyme.

The invention relates to a method of testing the activity of a potentially active substance to inhibit the enzymatic activity of phospholipase A2. The invention relates notably to a method wherein it comprises a) placing the potentially active substance in the presence with the phospholipase A2; a substrate which is a phospholipid, comprising at least one fatty acid in the form of an ester, the fatty acid is preferably a long chain having between 15 and 22 carbon atoms, this fatty acid preferably being unsaturated or poly-unsaturated, the substrate being capable of releasing at least one fatty acid during its hydrolysis; b) measuring the enzymatic activity of the phospholipase A2, notably comprising detecting the presence of the fatty acid and eventually its quantitative determination. The use of this test method notably enables identifying and selecting an active principle capable of inhibiting the enzymatic activity of phospholipase A2.

The invention relates to a quick detection method of dihydrogen-flavanol4-reductase / leucocyanidin reductase and anthocyanin reductase in tea tree, which can solve the problems of the prior technique of complicated operation in enzymatic activity detection method, high cost, long detection time. The quick detection method comprises: preparing an enzyme extracting-solution, measuring the protein content in enzyme extracting-solution and enzymatic activity, wherein the enzymatic activity is detected by detecting the consumption of the reduction type nicotinamide adenine dinucleotide phosphate solution (NADPH) and the vitamine C is added into the reaction system to reduce the interference of the substrate DHM and CYA on enzymatic activity detection. The quick detection method using ultraviolet spectrophotometer has features of simple method, low cost, short detection time of 15-25 minutes; environmental protection, safety, no need of noxious organic solvent, higher detection accuracy due to continuous detection of the changed enzymatic activity.

The invention relates to a C-type β-glucosidase mutant and its expression plasmid and recombinant bacteria, in particular to a C-type β-glucosidase mutant with significantly improved enzyme activity and a construction method thereof, belonging to biological engineering Technical field; The present invention carries out site-directed mutation on the β-glucosidase derived from Taiwan termites, and changes the lysine K at the 170th position into serine S and tryptophan W respectively, and the phenylalanine F at the 182nd position is methionine M, the amino acid histidine H at the 252nd position becomes asparagine N, and is respectively expressed as Glu1C-K170S, Glu1C-K170W, Glu1C-F182M, Glu1C-H252N; the obtained mutant of the present invention Enzyme activity has improved respectively 5.2 times, 2.05 times, 2.9 times, 2.1 times compared with before mutation; The application of biocatalytic technology provides a favorable basis for industrial application, can better meet the requirements of social production, and has broad market prospects.