Purification of two forms of bovine liver glycogen phosphorylase b with distinct subunit composition

The procedures for the purification of two forms of bovine liver glycogen phosphorylase b are described. Both forms showed a single band in nondenaturing gel electrophoresis. Gel electrophoresis in the presence of sodium dodecyl sulfate produced a single-band pattern for one of the enzyme forms (phosphorylase b1) and a triple-band pattern for the other (phosphorylase b3). Molecular weights associated with these bands were 97 kDa in the first case and 97, 55, and 40 kDa in the second. The yield from 1 kg of liver was approximately 10 mg for phosphorylase b1 and 140 mg for phosphorylase b3. The specific activity was 40-44 U/mg in both cases. As phosphorylase b1 is composed of just one kind of monomer, it is a novel bovine liver phosphorylase b structure.