[Interaction of substrates and their analogs with adenosylcobalamine-dependent glycerol dehydratase]

The interaction of AdoCbl-dependent glycerol dehydratase with the substrates (glycerol, 1,2-propandiol, ethylene glycol) and their analogs (aliphatic diols) was studied kinetically. It was found that all the diols tested are competitive inhibitors of the enzyme with respect to substrates. The arrangement of hydroxyl groups in the molecule, the length of the carbohydrate chain and the nature of the substituent at the C-3 atom are essential for the binding of diol in the active center. The ternary enzyme-AdoCbl-substrate (analog) complexes are subjected to specific inactivation at a rate, which depends on the chemical structure of the substrate (analog). The constants for inactivation and dissociation of the ternary complexes were determined. It was shown that in contrast to the double complexes (enzyme-AdoCbl), the inactivation of the ternary complexes does not depend on oxygen. Some aspects of the mechanism of specific inactivation of glycerol dehydratase are discussed.