title: Inactivation of phosphorylase b by potassium ferrate, a new reactive analogue of the phosphate group.
abstract: Rabbit muscle phosphorylase b reacts with the phosphate-like reagent potassium ferrate, K2FeO4, a potent oxidizing agent. The reaction results in inactivation of the enzyme and abolition of the ability of the enzyme to bind 5'-AMP. Activating and nonactivating nucleotides which bind at the 5'-AMP binding site such as 5'-AMP, 2'-AMP, 3'-AMP, and 5'-IMP substantially protect the enzyme from inactivation by ferrate. One to two residues of tyrosine and approximately 1 residue of cysteine are modified by ferrate under the conditions employed. Tyrosine is protected by 5-AMP, whereas cysteine is not. The tyrosine modification is suggested as the inactivating chemical reaction. The location of the inactivating reaction is suggested to be in or near the 5'-AMP binding site. The structural and chemical properties of ferrate ion are discussed and compared to those of phosphate. Ferrate ion may be a reagent useful for phosphate group binding site-directed modification of proteins.
mesh_terms: D000249:Adenosine Monophosphate / Q000494:pharmacology; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D007292:Inosine Nucleotides / Q000494:pharmacology; D007501:Iron / Q000494:pharmacology*; D007700:Kinetics; D046911:Macromolecular Substances; D009132:Muscles / Q000201:enzymology; D006005:Phosphorylases / Q000037:antagonists & inhibitors*; D011485:Protein Binding; D011817:Rabbits
chemical_list: D000596:Amino Acids; D007292:Inosine Nucleotides; D046911:Macromolecular Substances; D000249:Adenosine Monophosphate; D007501:Iron; D006005:Phosphorylases