These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Dual role of Zn2+ as inhibitor and activator of fructose 1,6-bisphosphatase of rat liver.
    Author: Tejwani GA, Pedrosa FO, Pontremoli S, Horecker BL.
    Journal: Proc Natl Acad Sci U S A; 1976 Aug; 73(8):2692-5. PubMed ID: 8778.
    Abstract:
    At neutral pH, Zn2+ is a potent and specific inhibitor of rat liver fructose 1,6-bisphosphatase (EC 3.1.3.11; D-fructose-1,6-bisphosphate 1-phosphohydrolase). Inhibition by Zn2+ is uncompetitive with respect to the activating cations Mg2+ and Mn2+, and the kinetic data suggest that the enzyme possesses a distinct high-affinity binding site for Zn2+, with Ki of approximately 0.3 muM. At higher concentrations (about 10(-5) M) Zn2+, and to a lesser extent Co2+, function as activating cations. Binding studies show that the enzyme binds two equivalents of Zn2+ per subunit; one equivalent is partially displaced by Mg2+ and is presumably bound to the site for activating cations. A second equivalent binds to the high-affinity site, presumably identical to the inhibitory site. The results suggest that Zn2+ functions as an allosteric regulator, and that the commonly observed activation of fructose 1,6-bisphosphatase at neutral pH by EDTA, histidine, and other chelators is due to removal of endogenous Zn2+ by these agents.
    [Abstract] [Full Text] [Related] [New Search]