K. Utsumi, T. Oda
Apr 1, 1969
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Journal
Archives of biochemistry and biophysics
Abstract
Abstract The effect of hydroxylamine on electron and energy transfer reactions has been investigated in rat liver mitochondria with the following results: 1. 1. Succinate oxidation is slightly inhibited by hydroxylamine in the absence of phosphate acceptor (state 4) and in the presence of uncoupler, but is strongly inhibited in the presence of a phosphate acceptor (state 3). Similar effect is observed with other substrates with the extent of inhibition increasing in the order of succinate > ascorbate > NAD-linked substrates. Hydroxylamine strongly inhibits soluble cytochrome oxidase activity but only partially retards terminal electron transfer in mitochondria. 2. 2. Hydroxylamine decreases the rate of energy transfer reactions such as reversed electron transfer, ion translocation, and ATP formation with Ki of 2 mM during succinate oxidation. ATP- 32 Pi exchange reaction and DNP-stimulated ATPase activity are not affected by hydroxylamine. 3. 3. Hydroxylamine does not inhibit the oxidation of fatty acids in the presence of carnitine, ATP, and uncoupler, suggesting that the reagent is not reacting with acyl compounds in mitochondria. It is concluded that hydroxylamine interacts at an early, as yet unidentified, energy transfer step in mitochondria.