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Updated: Jul 1, 2026

Direct Detection of the Acetate-forming Activity of the Enzyme Acetate Kinase
Published on: December 19, 2011
Relationship between substrate activity and pKa value of phenols on sulfotransferase from Eubacterium A-44
L Konishi-Imamura1, D H Kim, K Kobashi
1Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Japan.
Abstract:
The relationship between the kinetics of the enzyme activity and the structural features of phenolic donor and of acceptor substrates was investigated with a sulfotransferase from Eubacterium A-44, a human intestinal bacterium. The enzyme catalyzed the transfer of the sulfate group from the sulfate esters of phenol having a lower pKa to phenols having a higher pKa. When the Km values for acceptor substrates were measured at their optimal pH, a linear plot for log10Km versus the pKa with a slope of 0.615 was obtained. In addition, it is considered that the effect of pH on the Km values for the various acceptors is due to ionization of free enzyme. The kinetic behavior of bacterial sulfotransferase differed from that of mammalian phenol sulfotransferase.
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