Phosphoglucomutase

• Published in: The Journal of biological chemistry Vol. 241; no. 17; pp. 3940 - 3948
• Main Authors: Hashimoto, Takashi, Handler, Philip
• Format: Journal Article
• Language: English
• Published: American Society for Biochemistry and Molecular Biology 10.09.1966
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)99796-6

Procedures are described for the isolation of the phosphoglucomutases of flounder and shark muscle. Like the rabbit muscle enzyme, these exhibit a molecular weight of about 63,000 by ultracentrifugal and phosphate analysis, require α- d -glucose 1,6-diphosphate and Mg ++ for activity, are stimulated by preincubation with imidazoles and Mg ++ , and are phosphorylated by glucose 1,6-diphosphate and dephosphorylated by α- d -glucose 1-phosphate. Unlike rabbit muscle phosphoglucomutase, the flounder and shark enzymes are extremely labile below pH 5.0 and at pH 7.4 exhibit a significant level of glucose 1,6-diphosphatase activity. The activity of the flounder enzyme is doubled by formation of 1 mole of mercaptide of p -mercuribenzoate per mole of enzyme. Long after the reaction catalyzed by rabbit enzyme has come to thermodynamic equilibrium, the phosphate of glucose diphosphate fails to achieve isotopic equilibrium with that of the glucose monophosphates. The flounder P-glucomutase system behaves similarly, but isotopic equilibrium is achieved somewhat more rapidly than with the rabbit enzyme.