Electrophoretic purification of the alpha and beta subunits of phosphorylase kinase and evidence in support of the deduced amino acid sequences

A simple, rapid sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) method is presented for isolating the α, α' and β subunits of rabbit muscle phosphorylase kinase. The SDS‐PAGE procedure can yield milligram amounts of α and β from a single preparative gel and also allows isolation of the α' isozyme free of α. Notably the method provides the purified subunits in a form amenable to structural analysis. Edman degradation of α and α' reveal identical NH2‐terminal structures. Amino acid analysis of the electrophoretically purified α and β subunits are in good agreement with their deduced primary structures. The amino acid sequence of 488 residues in α and 713 residues in β were determined by gas phase Edman degradation. The data support the recently deduced primary structures of α (Zander et al., Proc. Natl. Acad. Sci. USA 1988, 85, 2929–2933) and of β (Kilimann et al., Proc. Natl. Acad. Sci. USA, 1988, 85, 9381–9385).