[Effect of environmental factors on inactivation of B12-dependent glycerol dehydratase from Aerobacter aerogenes].
Effect of temperature, pH and univalent cation on kinetics of self-activation of B12-dependent glycerol dehydratase (GD) from Aerobacter aerogenes with Co alpha-[alpha-(5,6-dimethylbenzimidazolyl]-Co beta-adenosylcobamide (AdoCbl) was investigated. The activation energy of the process of GD inactivation is found to be 3.9 kkal/M, the effect of pH on GD inactivation being insignificant. Monovalent cation is not required for the formation of GD-AdoCbl complex, but it protects the complex from selfinactivation. The rate of GD inactivation greatly depends on concentration of monovalent cations. Effect of K+, Rb+, Cs+, Tl+ and NH4+ cations, which are enzyme cofactors, qualitatively differs from the effect of Na+ and Li+, which are inactive in a catalytic reaction. The presence of at least two cation-binding sites in GD molecule is suggested. Possible mechanism of the effect of environmental factors in self-inactivation of GD-AdoCbl complex is discussed.
D001665:Binding Sites; D002384:Catalysis; D002414:Cations, Monovalent; D004754:Enterobacter / Q000201:enzymology*; D004755:Enterobacteriaceae / Q000201:enzymology*; D006836:Hydro-Lyases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D013696:Temperature
D002414:Cations, Monovalent; D006836:Hydro-Lyases
Vliianie faktorov sredy na inaktivatsiiu B12-zavisimoĭ glitseroldegidratazy iz Aerobacter aerogenes