Critical residues in D-amino acid oxidase. A pulse-radiolysis and inactivation study.
The enzyme D-amino acid oxidase and its apoenzyme have been irradiated at pH 5.5--10 under conditions designed to assess the inactivating effect of OH radicals and the selective free radicals Br2- and (SCN)2-. Near neutral pH, removal of the coenzyme FAD from the enzyme results in greater inactivation by selective free-radical attack. From pulse-radiolysis spectra, this increase is associated with attack on tyrosine and tryptophan residues in the protein. A large increase in inactivation of both the haloenzyme and apoenzyme by selective free-radical attack is seen with increasing alkalinity. This is consistent with attack on tyrosine being of major importance.
D000596:Amino Acids / Q000032:analysis*; D001051:Apoenzymes / Q000032:analysis / Q000528:radiation effects; D003605:D-Amino-Acid Oxidase / Q000032:analysis* / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005609:Free Radicals; D006863:Hydrogen-Ion Concentration; D011675:Pulse Radiolysis
D000596:Amino Acids; D001051:Apoenzymes; D005609:Free Radicals; D003605:D-Amino-Acid Oxidase