The conversion of lobster muscle phosphorylase a to b and phosphorylase b to a.

Lobster muscle phosphorylsse, in common with the phosphorylases of many other animal species, occurs in forms with different requirements for activity (1). Phosphorylase a is an active form; whereas phosphorylase 6 is active only in the presence of adenylic acid (AMP). It has been demonstrated with enzymes from mammalian species that phosphorylase may be converted from one form to another by reactions which are themselves enzyme catalyzed. One enzyme, from rabbit muscle (2) and dog heart muscle (3), catalyzes the conversion of phosphorylase a to phosphorylase b by removal of inorganic phosphate. This enzyme has been termed phosphorylase phosphatase (3). A second enzyme from dog (3) and rabbit (4) muscle catalyzes the conversion of phosphorylase b to phosphorylase a. The latter reaction involves the transfer of phosphate from ATP to the phosphorylsse molecule, and this enzyme has been named phosphorylase b kinase (4) or phosphokinase (3). The present paper will describe the extraction and partial purification of two analogous enzymes from lobster muscle which catalyze the conversion of lobster muscle phosphorylase a to b; and the reverse reaction, that of lobster phosphorylase b to a. The reactions catalyzed by these lobster enzymes have not been studied as thoroughly as those mentioned above for the mammalian species; but, in view of the similarities that have been found for the lobster and mammalian enzymes, the names lobster phosphorylase kinase and lobster phosphorylase phosphatase will be used.