Inhibition of mitochondrial substrate anion translocators by a synthetic amphipathic polyanion |
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Authors: | T. König I. Stipani I. Horvàth F. Palmieri |
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Affiliation: | (1) Second Institute of Biochemistry, Semmelweis University Medical School, 1088 Budapest, Hungary;(2) Institute of Biochemistry, Faculty of Pharmacy, Center for the Study of Mitochondria and Energy Metabolism, C.N.R., University of Bari, 70126 Bari, Italy |
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Abstract: | A synthetic polyanion (a copolymer of methacrylate, maleate, and styrene in 1:2:3 proportion with an average molecular weight of 10,000 dalton) inhibits the tricarboxylate, oxoglutarate, dicarboxylate, and adenine nucleotide translocators of rat liver mitochondria. The activity versus inhibitor concentration curves are sigmoidal. The inhibition of the oxoglutarate and tricarboxylate translocators by the polyanion is competitive, while that of the adenine nucleotide translocator is of mixed-type. TheK1 values of the polyanion are the following: for oxoglutarate translocator 4.0 µM, tricarboxylate translocator 1.2 µM, and adenine nucleotide translocator 1.3 µM with ADP and 0.8 µM with ATP. It is suggested that the polyanion acts primarily by increasing the negative charge of the inner membrane at the outer surface, and the sensitivity of the translocators toward the polyanion depends on the number of negative charges of their substrates. |
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Keywords: | Anion transport tricarboxylate 2-oxoglutarate adenine nucleotide polyanion inhibitor membrane transport |
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