title: Thiols of myosin. III. Spectrophotometric identification of the amino acid residue of myosin modified by rho-nitrobenzenediazonium fluoroborate.
abstract: As previously reported, rho-nitrobenzenediazonium fluoroborate strongly inhibits Ca2+- ATPase of myosin [EC 3.6.1.3] without appreciable suppression of its EDTA-K+- ATPase activity, and the presence of ATP in the reaction medium reverses the pattern of alteration in both ATPase activities, i.e., causing selective inhibition of EDTA-K+ -ATPase. Spectrophotometric studies on the azo-coupling products of 17 amino acids and their derivatives revealed that the amino acid residue of myosin modified by the diazonium dye was cysteine in both the presence and absence of ATP. It is also suggested that the number of cysteinyl residues responsible for the activity changes was one mole per mole of myosin subunit.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000596:Amino Acids; D001665:Binding Sites; D002118:Calcium / Q000494:pharmacology; D003979:Diazonium Compounds / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D009218:Myosins / Q000378:metabolism; D009578:Nitrobenzenes / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship
chemical_list: D000596:Amino Acids; D003979:Diazonium Compounds; D009578:Nitrobenzenes; D004492:Edetic Acid; D000251:Adenosine Triphosphatases; D009218:Myosins; D011188:Potassium; D002118:Calcium