title: Essentiality of the active-site arginine residue for the normal catalytic activity of Cu,Zn superoxide dismutase.
abstract: Chemical modification of bovine and yeast Cu,Zn superoxide dismutases with phenylglyoxal diminishes the catalytic activities by greater than or equal to 98%, and treatment of these enzymes with butanedione plus borate leads to greater than or equal to 96% inactivation. The activity loss is accompanied by the modification of less than two arginine residues per subunit with no concomitant loss of Cu or Zn. The phenylglyoxal-modified enzymes require at least a 20-fold greater concentration of cyanide for 50% inhibition than do the corresponding native enzymes. Polyacrylamide-gel electrophoresis and activity staining of the phenylglyoxal-inactivated enzymes demonstrate that the residual activity is largely associated with modified forms that bear lower net positive charge than the native superoxide dismutases.
mesh_terms: D001120:Arginine / Q000378:metabolism*; D001665:Binding Sites; D003486:Cyanides / Q000494:pharmacology; D003931:Diacetyl / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D010658:Phenylglyoxal / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D003486:Cyanides; D001120:Arginine; D013482:Superoxide Dismutase; D003931:Diacetyl; D010658:Phenylglyoxal