Purification of protein phosphatase from hen oviduct

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Abstract
Two protein phosphatases of 103 and 29 kDa as determined by gel filtration, were purified from hen oviducts. The 103 ‐kDa phosphatase was purified 7300‐fold to near homogeneity and dissociated into two polypeptides in the presence of SDS. Molecular masses of these polypeptides were estimated to be 60 and 38 kDa by SDS‐polyacrylamide slab gel electrophoresis using the buffer system of Laemmli, but 68 and 35 kDa using the buffer system of Weber and Osborn. The stoichiometry of these polypeptides was approx 1:1 according to the densitometric analysis of gels at 550 nm. The 29 ‐kDa phosphatase was purified 2900‐fold. Both phosphatases dephosphorylated the α‐subunit of phosphorylase kinase more rapidly than the β‐subunit.