Inactivation of enolase with tetranitromethane.
1. All 20 tyrosyl residues of enolase from human and pig muscle were nitrated with tetranitromethane in mild conditions; 2-phosphoglycerate and magnesium ions decreased the rate of reaction. 2. Inactivation took place in two steps: (a), nitration of 6 - 10 tyrosine residues of enolase decreased the activity by about 20%, without affecting Km value, molecular weight of pH dependence; (b) on nitration of 12 tyrosyl residues, inactivation was nearly complete, with concomitant profound changes in the enzyme properties. 2-Phosphoglycerate and magnesium ions present together protected significantly against inactivation. 3. The results suggest that the activity of enolase is dependent on intactness of tyrosyl residues.
D000818:Animals; D006801:Humans; D007700:Kinetics; D008697:Methane / Q000031:analogs & derivatives*; D009132:Muscles / Q000201:enzymology*; D010751:Phosphopyruvate Hydratase / Q000037:antagonists & inhibitors*; D013552:Swine; D013774:Tetranitromethane / Q000494:pharmacology*; D014443:Tyrosine
D014443:Tyrosine; D010751:Phosphopyruvate Hydratase; D013774:Tetranitromethane; D008697:Methane