Oxidative phosphorylation. XVI. Sulfhydryl involvement in the energy-transfer pathway

Abstract

The effect of organic mercurials was tested on the following energy-linked reactions in bovine heart submitochondrial particles: (a) reduction of nicctinamide-adenine dinucleotide by succinate coupled to the aerobic oxidation of ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine, (b) nicotinamide nucleotide transhydrogenase reaction (reduced nicotinamideadenine dinucleotide -, nicotinamide-adenine dinucleotide phosphate) driven by the energy from the oxidation of ascorbate-tetramethyl-p-phenylenediamine, and (c) energy-driven intravesicular acidification measured by the bromothymol blue color change. Reaction a was inhibited about 90% by 10 PM or less of mersalyl or mercuriphenylsulfonate. The energy-linked transhydrogenase reaction (reaction b) was also highly sensitive to mercurials under conditions in which the energy-

Differential effects of mercurial reagents on membrane thiols and on the permeability of the heart mitochondrion

“…It has been known for some time that CMB and other mercurials can promote swelling of isolated mitochondria (Tapley, 1956; Dickens and Salmony, 1956;Arcos et al, 1967) and result in increased turnover and net loss of endogenous K+ from mitochondria (Gamble, 1957; Scott and Gamble, 1961). In addition, mercurials have been found to inhibit respiration, uncouple phosphorylation, and interfere with the process of energy transport in submitochondrial particles (Kurup and Sanadi, 1968;Kielley, 1963;Boyer et al, 1966;Minakami et al, 1963). Despite these well-documented pathological effects of mercurials on mitochondrial activities, it has been established in our laboratory that under certain conditions mercurials activate the energy-linked accumulation of Mg2+ and K+ salts by intact mitochondria (Brierley et al, 1967(Brierley et al, , 1968a.…”

Chemical modification of mitochondrial transhydrogenase: evidence for two classes of sulfhydryl groups

“…Selective chemical modification of specific amino acid residues in the catalytic and putative proton-binding domains is the approach used here to evaluate the relationship between transhydrogenation and energy coupling. Sulfhydryl groups are essential for transhydrogenase activity (Humphrey, 1957; Kaufman and Kaplan, 1961; Kurup and Sanadi, 1968). A f From the Department of Chemistry, University of South Carolina, Columbia, South Carolina, 29208.…”

Oxidation of thioethers by bromine. A model system for oxidative phosphorylation

“…In order for the thioether group to be involved in biological oxidative phosphorylation, it is essential that thioethers and sulfoxides be oxidized and reduced, respectively, under biological conditions. The ability of thiols to reduce sulfoxides (Toennies and Kolb, 1939; Jori et al, 1968; Wallace and Weiss, 1966) has obvious implications for the well-documented role of thiols in oxidative phosphorylation (Kurup and Sanadi, 1968). Black et al (1960) have studied a system for the enzymatic reduction of l-(-)-methionine sulfoxide.…”