Galactaro δ-Lactone Isomerase: Lactone Isomerization by a Member of the Amidohydrolase Superfamily
摘要:
Agrobacterium tumefaciens strain C58 can utilize D-galacturonate as a sole source of carbon via a pathway in which the first step is oxidation of D-galacturonate to D-galactaro-1,5-lactone. We have identified a novel enzyme, D-galactarolactone isomerase (GLI), that catalyzes the isomerizaton of D-galactaro-1,5-lactone to D-galactaro-1,4-lactone. GLI; a member of the functionally diverse amidohydrolase superfamily, is a homologue of LigI that catalyzes the hydrolysis of 2-pyrone-4,6-dicarboxylate in lignin degradation. The ability of GLI to catalyze lactone isomerization instead of hydrolysis can be explained by the absence of the general basic catalysis used by 2-pyrone-4,6-dicarbolcylate lactonase.
carba Nicotinamide Adenine Dinucleotide Phosphate: Robust Cofactor for Redox Biocatalysis
作者:Ioannis Zachos、Manuel Döring、Georg Tafertshofer、Robert C. Simon、Volker Sieber
DOI:10.1002/anie.202017027
日期:2021.6.21
Here we report a new robust nicotinamidedinucleotidephosphate cofactor analog (carba-NADP+) and its acceptance by many enzymes in the class of oxidoreductases. Replacing one ribose oxygen with a methylene group of the natural NADP+ was found to enhance stability dramatically. Decomposition experiments at moderate and high temperatures with the cofactors showed a drastic increase in half-life time