The action of oligomycin and of para-hydroxymercuribenzoate on mitochondrial respiration stimulated by ADP, arsenate and calcium

Abstract

Thiols are involved in some substrate-level oxidative phosphorylation mechanisms. It is also possible that SH groups might play a role in electron transport phosphorylations. Recently Boyer (1965) proposed an acyl-S compound as a possible intermediate. Several compounds which react preferentially with SH groups were found to interfere with mitochondrial oxidative phosphorylation or its partial reactions. Para-hydroxymercuribenzoate (PMB) which is considered to be a relatively specific SH reagent, uncouples oxidative phosphorylation ( Lehninger, 1951; Cooper and Lehninger, 1956), abolishes 32P i - ATP exchange ( Cooper and Lehninger, 1957), inhibits the dinitrophenol-stimulated ATPase, activates the latent ATPase of mitochondria ( Kielley, 1963) and decreases the exchange of oxygen between water and inorganic phosphate ( Boyer, 1965). All these facts indicate that PMB-reactive groups are involved in the trapping of energy during oxidation. The present study was undertaken in order to localize the site of action of the mercurial in the energy transfer sequence and find the step where thiols might be involved.