On the mechanism of inhibition of fructose 1,6-bisphosphatase by fructose 2,6-bisphosphate |
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| Authors: | S Pontremoli E Melloni M Michetti F Salamino B Sparatore BL Horecker |
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| Institution: | 1. Institute of Biological Chemistry, University of Genoa, Genoa, Italy;2. Roche Institute of Molecular Biology, Nutley, New Jersey 07110 U.S.A. |
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| Abstract: | The inhibition of rabbit liver fructose 1,6-bisphosphatase (EC 3.1.3.11) by fructose 2,6-bisphosphate (Fru-2,6-P2) is shown to be competitive with the substrate, fructose 1,6-bisphosphate (Fru-1,6-P2), with Ki for Fru-2,6-P2 of approximately 0.5 μm. Binding of Fru-2,6-P2 to the catalytic site is confirmed by the fact that it protects this site against modification by pyridoxal phosphate. Inhibition by Fru-2,6-P2 is enhanced in the presence of a noninhibitory concentration (5 μm) of the allosteric inhibitor AMP and decreased by modification of the enzyme by limited proteolysis with subtilisin. Fru-2,6-P2, unlike the substrate Fru-1,6-P2, protects the enzyme against proteolysis by subtilisin or lysosomal proteinases. |
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| Keywords: | Author to whom all correspondence should be addressed |
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