title: Kinetic studies on a novel sulfotransferase from Eubacterium A-44, a human intestinal bacterium.
abstract: A novel sulfotransferase purified from a human intestinal bacterium stoichiometrically catalyzed the transfer of a sulfate group of phenylsulfate esters to phenolic compounds. Vmax values of the enzyme reaction were measured with various concentrations of a sulfate donor substrate, p-nitrophenylsulfate, and of a sulfate acceptor substrate, tyramine. Double reciprocal plots of the acceptor concentration and Vmax showed a linear correlation. One of the reaction products, tyramine O-sulfate, competitively inhibited the enzyme as to a donor substrate, p-nitrophenylsulfate (PNS), but the other reaction product, p-nitrophenol (PNP), noncompetitively inhibited it as to PNS. These kinetic data suggest that the sulfate transfer reaction proceeds according to a ping pong bi bi mechanism. The enzyme was activated by Mg2+ and inhibited by EDTA, which suggests that it is a metalloenzyme.
authors.affiliation: College of Pharmacy, Kyung-Hee University, Seoul, Korea.
authors.forename: D H
authors.initials: DH
authors.lastname: Kim
authors.forename: K
authors.initials: K
authors.lastname: Kobashi
mesh_terms: D001667:Binding, Competitive; D004492:Edetic Acid / Q000494:pharmacology; D005051:Eubacterium / Q000201:enzymology* / Q000302:isolation & purification; D006801:Humans; D007422:Intestines / Q000382:microbiology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009578:Nitrobenzenes; D013379:Substrate Specificity; D015238:Sulfotransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014439:Tyramine
chemical_list: D009578:Nitrobenzenes; C023379:4-nitrophenyl sulfate; D004492:Edetic Acid; D015238:Sulfotransferases; D008274:Magnesium; D014439:Tyramine