The allosteric properties of rat liver fructose-1,6-bisphosphatase

Meek, D.W. and Nimmo, H.G. (1984) The allosteric properties of rat liver fructose-1,6-bisphosphatase. Biochemical Journal, 222(1), pp. 131-138. (doi: 10.1042/bj2220131) (PMID:6089752) (PMCID:PMC1144153)

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Abstract

Inhibition of rat liver fructose-1,6-bisphosphatase by AMP was uncompetitive with respect to fructose 1,6-bisphosphate in the absence of fructose 2,6-bisphosphate, but non-competitive in its presence. AMP was unable to bind to the enzyme except in the presence of one of the fructose bisphosphates; the binding stoicheiometry was 2 molecules/tetramer. Increasing concentrations of Mg2+ increased the Hill coefficient h and the apparent Ki for AMP, whereas fructose 2,6-bisphosphate had the opposite effect. Increasing concentrations of both AMP and fructose 2,6-bisphosphate decreased h and increased the apparent Ka for Mg2+. AMP slightly decreased, and Mg2+ slightly increased, the apparent Ki for fructose 2,6-bisphosphate, but each had only small effects on h. These results are interpreted in terms of a new three-state model for the allosteric properties of the enzyme, in which fructose 2,6-bisphosphate can bind both to the catalytic site and to an allosteric site and AMP can bind to the enzyme only when the catalytic site is occupied.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Nimmo, Professor Hugh
Authors: Meek, D.W., and Nimmo, H.G.
College/School:College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:Biochemical Journal
Publisher:Portland Press
ISSN:0264-6021
ISSN (Online):1470-8728

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