GLYCOGEN PHOSPHORYLASE SYSTEM FROM MUSCLE OF BLUE CRAB - CALLINECTES DANAE

1. 1. Glycogen phosphorylase in extracts from blue crab muscle, Callinectes danae, was assayed at pH 6·6 in presence of cysteine. 2. 2. Two interconvertible forms of the enzyme are present: b has a total AMP* requirement for activity; a partial requirement. The b to a conversion requires ATP and kinase which precipitates at pH 5·7; the a to b conversion is fluoride sensitive. 3. 3. A large proportion of bound activity which is released by ATP appears to be b tightly bound to the kinase. 4. 4. AMP partially protects a against inhibition by p-mercuribenzoate at 10-4 M, fully at 10-5 M, but cannot protect b. The inhibition is reversed by cysteine. © 1969.