Solubilization of adenylate cyclase of brain membranes by lipid peroxidation |
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Authors: | Eibai Lee Akemichi Baba Akira Ohta Heitaroh Iwata |
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Institution: | Department of Pharmacology, Faculty of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka Japan |
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Abstract: | Adenylate cyclase in the membrane fractions of bovine and rat brains, but not in rat liver plasma membranes, was solubilized by treatment with Fe2+ (10 μM) plus dithiothreitol (5 mM). Solubilization of the enzyme by these agents was completely prevented by simultaneous addition of N,N′-diphenyl-p-phenylenediamine (DPPD), an inhibitor of lipid peroxidation. Ascorbic acid also solubilized the enzyme from the brain membranes. Lipid peroxidation of the brain membranes was characterized by a selective loss of phosphatidylethanolamine. Solubilization of membrane-bound enzymes by Fe2+ plus dithiothreitol was not specific for adenylate cyclase, because phosphodiesterase, thiaminediphosphatase and many other proteins were also solubilized. Solubilized adenylate cyclase had a high specific activity and was not activated by either NaF, 5′-guanylyl imidodiphosphate (GppNH]p) or calmodulin. These results suggested that lipid peroxidation of the brain membranes significantly solubilized adenylate cyclase of high specific activity. |
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Keywords: | Enzyme solubilization Adenylate cyclase Lipid peroxidation Brain membrane (Bovine cerebral cortex) DPPD Gpp[NH]p 5′-guanylyl imidodiphosphate |
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