ISSN:
1573-4919
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Summary Hepatic pyruvate kinase phosphatase activity has been assayed in native conditions, in Sephadex G-25 filtrated extracts of rat hepatocytes, by measuring the reactivation rate of glucagon-inactivated pyruvate kinase-L. The ionic requirements for this reaction, as well as the possible regulatory role of some pyruvate kinase ligands, have been investigated. Pyruvate kinase phosphatase activity was dependent on divalent cations (Mg2+, Mn2+ or Co2+. Mg2+ ions highly enhanced the reactivation rate of pyruvate kinase, while the presence of 100 mM KF inhibited this process. Physiological concentrations of phosphoenolpyruvate or fructose 1,6-bisphosphate inhibited pyruvate kinase phosphatase activity. These inhibitory effects were partially antagonized by the presence of L-alanine. Our results suggest that ligands of pyruvate kinase could play a role in the control of pyruvate kinase phosphatase activity(ies), possibly by modifying the conformational state of the substrate protein.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00230395
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