Regulation by Phosphoenolpyruvate of Fructose-1,6-diphosphatase in Skeletal Muscle: Evidence for an Allosteric Activator of the Enzyme

1 June 1972

journal article
Published by Canadian Science Publishing in Canadian Journal of Biochemistry

Vol. 50 (6) , 710-713
https://doi.org/10.1139/o72-098

Abstract

Fructose-1,6-diphosphatase (FDPase) from muscle of three cold-water crustaceans was found to be activated by phosphoenolpyruvate (PEP). PEP appears to reduce K_m for FDP at low and high temperatures; however, at low temperature the effect on K_m of FDP is amplified. In addition PEP reduces affinity of FDPase for AMP, the allosteric inhibitor of the enzyme. These results suggest a coupling of several of the regulatory steps in the glycolytic and gluconeogenic sequences. In addition, skeletal muscle of the crustaceans used in the present study contains substantial (higher than 500 μmol/h/g tissue) activities of the gluconeogenic enzymes phosphoenolpyruvate carboxykinase, pyruvate carboxylase, and glucose-6-phosphatase. On the basis of these results it is proposed that gluconeogenesis is a functioning pathway in crustacean muscle.

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