Release of Brain Mitochondrial Hexokinase by Acidic Proteins and Macromolecular Polyanions
Abstract
Description
Preparations of arachidonic acid binding and non-binding proteins from bovine brain, four acidic proteins (alpha-casein, phosvitin, beta-lactoglobulin A and B), the peptide polyglutamate, and two polyanions (heparin, dextran sulfate) enhanced both basal and glucose 6-phosphate induced solubilization of rat brain mitochondrial hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1). In contrast, three other acidic proteins, had little (alpha-lactalbumin) or no effect (bovine serum albumin, ovalbumin) and five basic proteins inhibited release of the enzyme. Solubilizing activity therefore appears to require a net negative charge and one or more of the following structural features: extended conformation, random coil, and unordered or beta-structure, in the latter case, as the beta-barrel in the fatty acid binding proteins and beta-lactoglobulins. It is of interest that a difference of a single negative charge between beta-lactoglobulin A and B, resulted in a statistically significant difference in the stimulation of hexokinase release. Possible physiological and pathological roles of this hexokinase solubilizing effect are discussed briefly.
29 pages,3 figures. Figures and page number revised(28 pages)
29 pages,3 figures. Figures and page number revised(28 pages)