title: Phenylglyoxal inactivation of the mitochondrial adenosine triphosphatase from Trypanosoma cruzi.
abstract: The reaction of Trypanosoma cruzi Mg2+-stimulated adenosine triphosphatase (ATPase, coupling factor 1, or F1) with phenylglyoxal, a dicarbonylic compound, resulted in a rapid loss of its enzymatic activity. The inactivation showed pseudo-first-order kinetics with both membrane-bound and soluble F1-ATPase, the rate of the enzyme inactivation being faster in bicarbonate buffer (pH 7.9) than in borate buffer (pH 8.0). The log (pseudo-first-order rate constant) vs. log(phenylglyoxal concentration) plots obtained with the membrane-bound and soluble F1-ATPase in bicarbonate buffer, and also with F1 in borate buffer, had slopes of near 1.0 while the plot for the membrane-bound ATPase in borate buffer had a slope of 1.6. Second-order rate constants (in mM-1 X min-1) were 55 (for both ATPase preparations in bicarbonate buffer) and 34 (for the membrane-bound ATPase in borate buffer). When the reaction was performed in the presence of ATP, the rate of inactivation was significantly decreased. It is concluded that, as in the mammalian F1-ATPase, arginyl residues play an essential role in T. cruzi mitochondrial ATPase, probably at the hydrolytic site.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000447:Aldehydes / Q000494:pharmacology*; D000818:Animals; D008928:Mitochondria / Q000201:enzymology; D010658:Phenylglyoxal / Q000494:pharmacology*; D014349:Trypanosoma cruzi / Q000201:enzymology* / Q000648:ultrastructure
chemical_list: D000447:Aldehydes; D000251:Adenosine Triphosphatases; D010658:Phenylglyoxal