Kinetic Studies on a Sulfotransferase from Klebsiella K-36, a Rat Intestinal Bacterium

Sulfotransferase purified from Klebsiella K-36, a rat intestinal bacterium, stoichiometrically catalyzed the transfer of a sulfate group of phenylsulfate esters to phenolic compounds. One of the reaction products, p-nitrophenol (PNP), non-competitively inhibited the enzyme as to p-nitrophenylsulfate (PNS), a donor substrate, but competitively inhibited the enzyme as to an acceptor substrate, a-naphthol. The other reaction product, a-naphthol-0-sulfate, non-competitively inhibited the enzyme with regard to both these substrates. These kinetic data suggest that the sulfotransferase reaction proceeds according to an ordered bi bi reaction mechanism. The natural phenolic substances, gallic acid, quercetin, tannic acid, and serotonin were good substrates of K-36 sulfotransferase.