title: Bovine cardiac myosin subfragment 1. Transient kinetics of ATP hydrolysis.
abstract: The kinetics of binding and hydrolysis of ATP by bovine cardiac myosin subfragment 1 has been reinvestigated. More than 90% of the total fluorescence amplitude associated with ATP hydrolysis occurs with an apparent second-order rate constant of 8.1 X 10(5) M-1 S-1 and a limiting rate constant of approximately 140 S-1 (100 mM KCl, 50 mM 1,3-bis-[tris(hydroxymethyl)methylamino]-propane, 10 mM MgCl2, pH 7.0, 20 degrees C); the remaining 10% occurs more slowly (approximately 1 S-1). The observed rate constants are independent of subfragment 1 concentration under pseudo first-order conditions for ATP with respect to protein. The fraction of protein which hydrolyzes ATP rapidly is not a function of the nucleotide or protein concentration and appears to be constant irrespective of ionic strength or temperature within the range studied (50-100 mM KCl, pH 7.0, 15-20 degrees C). These data are compared to that obtained previously using subfragment 1 prepared by a different method which showed ATP-dependent aggregation of two protein species.
mesh_terms: D000199:Actins / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D002417:Cattle; D006868:Hydrolysis; D007700:Kinetics; D009025:Morpholines / Q000494:pharmacology; D009206:Myocardium / Q000201:enzymology*; D015879:Myosin Subfragments; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D014325:Tromethamine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000199:Actins; D009025:Morpholines; D015879:Myosin Subfragments; D010446:Peptide Fragments; D014325:Tromethamine; C008550:morpholinopropane sulfonic acid; C034249:1,3-bis(tris(hydroxymethyl)methylamino)propane; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D009218:Myosins