Studies on Galactosyltransferase

The forward reaction catalyzed by galactosyltransferase has been studied kinetically at pH 8.0 with N-acetylglucosamine as the galactosyl group acceptor. From the results of initial velocity studies, as well as investigations of the deadend inhibition by UDP-glucose and the substrate inhibition by higher concentrations of N-acetylglucosamine, it has been concluded that the reaction has an ordered mechanism with the reactants adding in the order: Mn2+, UDP-galactose, N-acetylglucosamine. A further conclusion is that Mn2+ reacts with the free enzyme under conditions of thermodynamic equilibrium and does not dissociate after each catalytic cycle. Values are reported for the various kinetic parameters.