[Reactivity and specificity of alpha-dicarbonyl compounds towards essential aminoacyl residues of D-beta-hydroxybutyrate dehydrogenase from the inner mitochondrial membrane].
The effects of a alpha-dicarbonyl chromophoric reagent: 4-hydroxy-3-nitrophenylglyoxal on the D-beta-hydroxybutyrate dehydrogenase have been compared to those of phenylglyoxal, a specific arginyl reagent in proteins. Both reagents inactivate irreversibly the enzyme. Kinetic experiments show that only one molecule of these reagents per molecule of enzyme is sufficient to inactivate the enzyme. The second order inactivation rate constant is more than 500 times higher with the chromophoric reagent than with phenylglyoxal. A pseudosubstrate (methylmalonate) in presence of coenzyme (NAD) strongly protects enzyme against inactivation by both reagents. Coenzyme alone has no effect on inactivation by phenylglyoxal while it protects whether inhibitor is the chromophoric reagent or N-ethylmaleimide: a thiol specific reagent. These results indicate: 1. That one arginyl residue is essential for D-beta-hydroxybutyrate dehydrogenase activity (experiments with phenylglyoxal). 2. That the presence of a nitro group on position 3 and a hydroxyl-group on position 4 strongly increase the reactivity of the alpha-dicarbonyl groups, but the specificity of the chemical reaction with arginyl residues seems to be lost for the benefit of cysteyl residues.
D015111:4-Hydroxyphenylpyruvate Dioxygenase / Q000494:pharmacology*; D000447:Aldehydes / Q000494:pharmacology*; D000818:Animals; D005033:Ethylmaleimide / Q000494:pharmacology; D006884:Hydroxybutyrate Dehydrogenase / Q000378:metabolism*; D007425:Intracellular Membranes / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology*; D009243:NAD; D010105:Oxygenases / Q000494:pharmacology*; D010658:Phenylglyoxal / Q000494:pharmacology*; D011485:Protein Binding; D051381:Rats; D013329:Structure-Activity Relationship
D000447:Aldehydes; D009243:NAD; D006884:Hydroxybutyrate Dehydrogenase; D010105:Oxygenases; D015111:4-Hydroxyphenylpyruvate Dioxygenase; D010658:Phenylglyoxal; D005033:Ethylmaleimide
Réactivité et spécificité de composés alpha-dicarbonylés vis-à-vis de résidus aminoacyl essentiels à l'activité de la D-beta-hydroxybutyrate déshydrogénase de la membrane interne mitochondriale.