Equilibrium constant of phosphoryl transfer from adenosine triphosphate to galactose in the presence of galactokinase

Abstract

Electrophoretic and enzymic methods are described for specific estimation of compounds present in the equilibria ATP + ([alpha] + [beta]-D-galactoses[image]ADP + [alpha]-D-galactose 1-phosphate, and 2ADP[image]AMP + ATP, which are catalyzed by galactokinase and adenylate kinase respectively. A general spectro-photometric estimation of the substrates of kinases is described. The equilibrium constant of the galactokinase reaction, [ADP] [[alpha]-D-galactose 1 -phosphate]/[ATP] [([alpha] +[beta])-D-galactose] was 26 at pH 7.00 and 25[degree] in the presence of 25 mM-Mg2+. The equilibrium constant of the adenylate kinase reaction, [ADP]2/[AMP] [ATP] at pH 7.00 and 25[degree] was 2.1 with 10 mM-Mg2+ and 3-6 with 25 mM-Mg2+.