STRUCTURE AND FUNCTION OF 2 HEADS OF MYOSIN MOLECULE .2. SEPARATION OF 2 FRACTIONS OF SUBFRAGMENT-1 OF MYOSIN BY AFFINITY COLUMN CHROMATOGRAPHY ON IMMOBILIZED F-ACTIN - DIRECT EVIDENCE FOR ACCELERATION BY F-ACTIN OF DECOMPOSITION OF REACTIVE ENZYME-PHOSPHATE-ADP COMPLEX FORMED ON HEAD-B OF MYOSIN