title: Chemical modification studies on arginine kinase: essential cysteine and arginine residues at the active site.
abstract: Chemical modification was used to elucidate the essential amino acids in the catalytic activity of arginine kinase (AK) from Migratoria manilensis. Among six cysteine (Cys) residues only one Cys residue was determined to be essential in the active site by Tsou's method. Furthermore, the AK modified by DTNB can be fully reactivated by dithiothreitol (DTT) in a monophasic kinetic course. At the same time, this reactivation can be slowed down in the presence of ATP, suggesting that the essential Cys is located near the ATP binding site. The ionizing groups at the AK active site were studied and the standard dissociation enthalpy (DeltaH degrees ) was 12.38kcal/mol, showing that the dissociation group may be the guanidino of arginine (Arg). Using the specific chemical modifier phenylglyoxal (PG) demonstrated that only one Arg, located near the ATP binding site, is essential for the activity of AK.
authors.affiliation: College of Life Science, Shandong Agricultural University, Shandong Taian 271018, People's Republic of China.
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Zhu
authors.forename: Miao
authors.initials: M
authors.lastname: Li
authors.forename: Xiao-Yun
authors.initials: XY
authors.lastname: Wang
mesh_terms: D000818:Animals; D001120:Arginine; D001122:Arginine Kinase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D003545:Cysteine; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006110:Grasshoppers / Q000201:enzymology; D019476:Insect Proteins / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D013053:Spectrophotometry; D013816:Thermodynamics
chemical_list: D004791:Enzyme Inhibitors; D019476:Insect Proteins; D001120:Arginine; D004228:Dithionitrobenzoic Acid; D001122:Arginine Kinase; D003545:Cysteine; D004229:Dithiothreitol