Isolation and physicochemical properties of active complexes of rabbit muscle phosphorylase kinase.

Abstract

A catalytically active species composed of a, y, and 8 subunits was isolated from phosphorylase kinase.Upon incubation of the holoenzyme ( c u s y S ) 4 with 1.8 M LiBr, 10 m~ LiBr, 10 m~ M&+ at 0 "C for 6-7 h and subsequent gel filtration and ion exchange chromatography, an active ayS complex was purified to apparent homogeneity by the criteria of gel filtration, disc gel electrophoresis under denaturing and nondenaturing conditions, and sucrose density gradient sedimentation.The ayS complex was shown to have a molecular weight of 243,000 by gel filtration and stoichiometric amounts of a, y, and S subunits by densitometric tracings, suggesting that it is a monomer.A species containing the catalytically active y subunit isolated previously (Skus-