title: Structure and function of the two heads of the myosin molecule. II. Separation of the two fractions of subfragment-1 of myosin by affinity column chromatography on immobilized F-actin: direct evidence for acceleration by F-actin of the decomposition of the reactive enzyme-phosphate-ADP complex formed on head B of myosin.
abstract: F-Actin (FA) and pyruvate kinase (PK) [EC 2.7.1.40] were immobilized on PAB-cellulose. HMM-Subfragment-1 (S-1) was applied to a column of immobilized FA and PK, and eluted with 1-1.5 muM ATP and 1 mM PEP in 50 mM KCl, 2 mM MgCl2, and 10 mM Tris-HCl at pH 7.8 and 4 degrees. The size of the initial burst of Pi liberation of S-1 applied to the column was 0.5 mole/mole S-1. The burst size of S-1 decreased with increase in the fraction number, and S-1 in later fractions showed a burst size of 0.1-0.3 mole/mole. On the other hand, the rate of the ATPase [EC 3.6.1.3] reaction in the steady state was almost independent of the burst size, and increased slightly with increase in the fraction number. The ATPase activity of S-1 with a burst size of less than 0.2 mole/mole was scarcely activated by FA. Usually, the dependence on the burst size of S-1 of its ATPase activity in the presence of FA was sigmoidal, and marked activation by FA was observed when the burst size was larger than 0.3-0.4 mole/mole. Similar results were obtained with S-1 fractions separated by the ultracentrifugation method described in our previous paper ((1976) J. Biochem. 79, 419-434).
mesh_terms: D000199:Actins / Q000494:pharmacology*; D000244:Adenosine Diphosphate / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002846:Chromatography, Affinity; D004800:Enzymes, Immobilized; D015879:Myosin Subfragments; D010446:Peptide Fragments / Q000302:isolation & purification; D010710:Phosphates / Q000378:metabolism; D011485:Protein Binding; D011770:Pyruvate Kinase; D011817:Rabbits
chemical_list: D000199:Actins; D004800:Enzymes, Immobilized; D015879:Myosin Subfragments; D010446:Peptide Fragments; D010710:Phosphates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011770:Pyruvate Kinase; D000251:Adenosine Triphosphatases; D002118:Calcium