title: Arginyl residues of adrenodoxin reductase as the anion recognition site for 2'-phosphate group of NADP+1.
abstract: Adrenodoxin reductase from bovine adrenocortex was inactivated by arginine specific reagents, p-hydroxyphenylglyoxal, phenylglyoxal, 2,3-butanedione, and 1,2-cyclohexanedione. Inactivation of the enzyme caused by p-hydroxyphenylglyoxal obeyed pseudo-first-order kinetics and resulted in complete elimination of NADPH-ferricyanide reductase activity. The rate of inactivation increased with pH from 6.5 to 9.5. Ten out of 30-33 arginyl residues of the enzyme were modified, but residues essential to its enzymatic activity were less than 5. NADP+ strongly protected against inactivation by p-hydroxyphenylglyoxal, whereas NAD+ could afford only partial, weak protection. Furthermore, 2'-AMP and 2',5'-ADP afforded considerable protection but 5'-AMP did not. These data suggest that adrenodoxin reductase has essential arginyl residues which are crucial to the enzymatic activity as the recognition site for the negatively charged 2'-phosphate group of NADP+.
mesh_terms: D000818:Animals; D000838:Anions / Q000378:metabolism; D001120:Arginine / Q000378:metabolism*; D001665:Binding Sites; D002417:Cattle; D005287:Ferredoxin-NADP Reductase / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism
chemical_list: D000838:Anions; D010710:Phosphates; D009243:NAD; D009249:NADP; D001120:Arginine; D005287:Ferredoxin-NADP Reductase; D009247:NADH, NADPH Oxidoreductases