Cloning and characterization of the β-xylosidase from Dictyoglomus turgidum for high efficient biotransformation of 10-deacetyl-7-xylosltaxol
摘要:
With the aim of finding an extracellular biocatalyst that can efficiently remove the C-7 xylose group from 10-deacetyl-7-xylosltaxol, a Dictyoglomus turgidum beta-xylosidase was cloned and expressed in Escherichia coli BL21 (DE3). The molecular mass of purified Dt-Xyl3 was approximately 84 kDa. The recombinant Dt-Xyl3 was most active at pH 5.0 and 75 degrees C, retaining 88% activity at 65 degrees C for 1 h, and displaying excellent stability over pH 4.0-7.5 for 24 h. In terms of kinetic parameters, the K-m and V-max values for pNPX were 0.8316 mM and 5.0178 mu mol/mL.min, respectively. Moreover, Dt-Xyl3 was activated by Mn(2+)and Ba2+ and inhibited by Cu2+, Ni+ and Al3+. In particular, it displayed high tolerance to salts with 60.8% activity in 20% (w/v) NaCl. Ethanol and methanol at 5-15% showed little effect on the enzymatic activity. Dt-Xyl3 demonstrated multifunctional activities followed by pNPX, pNPAraf and pNPG and had a high selectivity for cleaving the outer xylose moieties of 10-deacetyl-7-xylosltaxol with K-cat/K-m 110.87 s(-1)/mM, which produced 10-deacetyl-taxol to semi-synthesize paclitaxel. Under the optimized conditions (60 degrees C, pH 4.5, enzyme dosage of 0.5 U/mL), 1 g of 10-deacetyl-7-xylosltaxol was transformed to its corresponding aglycone 10-deacetyl-taxol within 30 min, with a molar conversion of 98%. This is the first report that Dictyoglomus turgidum can produce extracellular GH3 beta-xylosidase with highly specific activity for 10-deacetyl-7-xylosltaxol biotransformation, thus leading to the application off beta-xylosidase Dt-Xyl3 as a biocatalyst in biopharmaceutics.
Synthesis of Novel Di- and Trisaccharide Mimetics with Non-Glycosidic Amino Bridges
作者:Janna Neumann、Saskia Weingarten、Joachim Thiem
DOI:10.1002/ejoc.200600958
日期:2007.3
Synthesis of novel di- and trisaccharides using enzymatic glycosylation, Dess–Martin oxidation and reductive amination allows rapid access to the target structures. Thus, a novel class of glycomimetics was obtained having nitrogen inserted as bridging atom between two non-anomeric positions. Novel di- and trisaccharide mimetics were designed using N-acetylglucosamine as a basis structure. A third monosaccharide
A selective agent comprising a triclosan derivative for use in selective inhibition of non-target cells in a mixed population of target and non-target cells. Preferably the triclosan derivative is a glycoside derivative, more preferably a pyranoside derivative. Suitably a selective medium comprising said selective agent and methods of culturing cells using the selective agent are provided.
Engineered enzymes and their use for synthesis of thioglycosides
申请人:Withers G Stephen
公开号:US20060035342A1
公开(公告)日:2006-02-16
Mutant glycosidases in which the amino acid in the active site that serves as the acid, base or acid/base-catalyst is converted from a carboxylic acid to some other amino acid (for example to a simple alkyl, as in alanine or glycine) can catalyze the reaction of a thiosugar acceptor and an activated donor to form a thioglycoside. The “thioglycoligases” represent a novel class of mutant enzymes, and represent a first aspect of the invention. Thioglycoligases can be used in accordance with the method of the invention to couple a thiosugar acceptor and an activated donor to form a thioglycoside. By selection of the donor and acceptor species, as well as the specific enzyme employed, thioglycosides of different structure and stereochemistry can be obtained.
Engineered Enzymes and Their Use for Synthesis of Thioglycosides
申请人:Withers G. Stephen
公开号:US20070004010A1
公开(公告)日:2007-01-04
Mutant glycosidases in which the amino acid in the active site that serves as the acid, base or acid/base-catalyst is converted from a carboxylic acid to some other amino acid (for example to a simple alkyl, as in alanine or glycine) can catalyze the reaction of a thiosugar acceptor and an activated donor to form a thioglycoside. The “thioglycoligases” represent a novel class of mutant enzymes, and represent a first aspect of the invention. Thioglycoligases can be used in accordance with the method of the invention to couple a thiosugar acceptor and an activated donor to form a thioglycoside. By selection of the donor and acceptor species, as well as the specific enzyme employed, thioglycosides of different structure and stereochemistry can be obtained.
NOVEL GLYCOSYL HYDROLASE WITH BETA-XYLOSIDASE AND BETA-GLUCOSIDASE ACTIVITIES AND USES THEREOF
申请人:Zhu Ping
公开号:US20130130330A1
公开(公告)日:2013-05-23
A novel glycosyl hydrolase with activities of beta-xylosidase and beta-glucosidase is provided. Said glycosyl hydrolase can convert 7-xylosyltaxane compounds to 7-hydroxyltaxane compounds.