title: Myelin basic protein inhibits histone-specific protein methylase I.
abstract: Bovine brain myelin basic protein, free of associated proteolytic activity, was found to be a specific inhibitor of histone-specific protein methylase I (S-adenosyl-L-methionine:protein-L-arginine N-methyltransferase, EC 2.1.1.23) purified from bovine brain. 50% of the methyl group incorporation into the histone substrate catalyzed by the methylase I was inhibited by myelin basic protein at a concentration of 0.326 mM. However, neither of the peptide fragments (residues 1-116 and residues 117-170) generated by the chemical cleavage of myelin basic protein at the tryptophan residue retained the inhibitory activity for histone-specific protein methylase I. Proteins such as gamma-globulin, bovine serum albumin, bovine pancreatic ribonuclease and polyarginine did not exhibit significant inhibitory activity toward the enzyme. The Ki value for myelin basic protein was estimated to be 3.42 X 10(-5) M for histone-specific protein methylase I and the nature of the inhibition was uncompetitive toward histone substrate.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology; D002417:Cattle; D006657:Histones / Q000378:metabolism*; D008745:Methylation; D004676:Myelin Basic Protein / Q000494:pharmacology*; D011496:Protein Methyltransferases / Q000037:antagonists & inhibitors*; D011484:Protein-Arginine N-Methyltransferases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification
chemical_list: D000596:Amino Acids; D006657:Histones; D004676:Myelin Basic Protein; D011496:Protein Methyltransferases; D011484:Protein-Arginine N-Methyltransferases