title: Nitric oxide regulation of glyceraldehyde-3-phosphate dehydrogenase activity in Dictyostelium discoideum cells and lysates.
abstract: The ability of compounds releasing nitric oxide (NO) to regulate glyceraldehyde-3-phosphate dehydrogenase (GraPDH) activity was analysed both in cell homogenates and in intact Dictyostelium discoideum. The time course of GraPDH inactivation in cell lysates by NO-releasing compounds suggests that two processes may be involved, one of which accounts for the majority of the inactivation and shows a close correlation with GraPDH ADP-ribosylation. Maximal ADP-ribosylation under these conditions exhibited a stoichiometry of about 0.4 mol ADP-ribose/mol enzyme tetramer. NO-mediated inhibition of GraPDH activity was attenuated if specific substrates, cofactors, or cysteine were added to cytosol preparations. Under such conditions, ADP-ribosylation of the enzyme was correspondingly reduced or negligible. Intact cells treated with NO-releasing compounds were shown to respond by rapidly decreasing their GraPDH activity. This inhibition was transient and, after a 10-min incubation, enzyme activity returned to the level seen in control cells. The time course of these in vivo changes correlated well with those of the NO-stimulated ADP-ribosylation of GraPDH also seen in intact cells. The basis underlying the NO-stimulated inhibition of GraPDH activity was investigated and found to reflect a decreased Vmax. No changes in either the Km of the enzyme for its substrates or its state of polymerization were observed.
authors.affiliation: E. A. Doisy Department of Biochemistry and Molecular Biology, St Louis University School of Medicine, MO 63104.
authors.forename: Y
authors.initials: Y
authors.lastname: Tao
authors.forename: A
authors.initials: A
authors.lastname: Howlett
authors.forename: C
authors.initials: C
authors.lastname: Klein
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D003545:Cysteine / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D004023:Dictyostelium / Q000201:enzymology*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D009243:NAD / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology*; D010084:Oxidation-Reduction
chemical_list: D009243:NAD; D009599:Nitroprusside; D000246:Adenosine Diphosphate Ribose; D009569:Nitric Oxide; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D003545:Cysteine