title: [Substrate specificity of adenosylcobalamin-dependent glycerol dehydratase. Interaction with enantiomers of 1,2-propanediol].
abstract: Adenosylcobalamin-dependent glycerol dehydratase was shown to catalyze the conversion of both enantiomers of 1.2-propanediol. The kinetic constants for the dehydration reaction of (R)- and (S)-1.2-propanediol appear to be different. The enzyme preferentially binds 1.2-propanediol in the (S)-configuration; however, the rate of (S)-1,2-propanediol dehydration is 2 times less than that of (R)-1.2-propanediol. The catalytic conversion of 1.2-propanediol enantiomers is accompanied by the enzyme inactivation. During dehydration of (R)-1.2-propanediol the enzyme is inactivated at a higher rate than during the (S)-enantiomer dehydration. The turnover number of the enzyme calculated as a ratio of the rate constants of catalysis and inactivation does not practically depend on the substrate configuration. Consequently, the changes in the configuration of the substrate, 1.2-propanediol, similarly affect the rate-limiting steps of the catalytic and inactivation processes. It is assumed that the (R)- and (S)-enantiomers of 1.2-propanediol are bound at the substrate site of glycerol dehydratase by three identical points.
mesh_terms: D003038:Cobamides / Q000494:pharmacology*; D006801:Humans; D006836:Hydro-Lyases / Q000378:metabolism*; D007536:Isomerism; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000201:enzymology; D008875:Middle Aged; D019946:Propylene Glycol; D011409:Propylene Glycols; D013379:Substrate Specificity
chemical_list: D003038:Cobamides; D011409:Propylene Glycols; D019946:Propylene Glycol; D006836:Hydro-Lyases; C020671:glycerol dehydratase; C000913:cobamamide
vernacular_title: Substratnaia spetsifichnost' adenozilkobalaminzavisimoĭ glitseroldegidratazy. Vzaimodeĭstvie s énantiomerami 1,2-propandiola.