M. Esposti, G. Lenaz
Jun 1, 1982
Citations
2
Influential Citations
24
Citations
Journal
FEBS Letters
Abstract
Antimycin A is a potent inhibitor of mitochondrial and microbial electron-transfer chains [ 1 ]; it stoichiometrically binds to the bcl complex of such systems [1 ] inducing a typical crossover in the redox state of cytochromes b and c [2]. The mechanism of action of antimycin is not yet clearly elucidated, and constitutes a key problem in the interpretation of the redox events in the bc~ region. Evidence against a simple linear pathway of electron transfer in this span of the mitochondrial respiratory chain has been collected by a number of experimental observations on the effects of the antibiotic, including the oxidant-induced extra-reduction of cytochromes b [3] and the slower reduction of cytochromes b when cytochrome cl is previously reduced [4]. The protonmotive Q-cycle of Mitchell [5] and variations thereof [6,7] or different cyclic schemes [8] have been proposed to explain the above and other experimental observations. Such schemes postulate that the first oxidant of ubiquinol is a redox center located at the cytoplasmic side of the mitochondrial membrane (generally identified as the i ronsulfur protein of the bc~ complex [6,7,9]) which delivers electrons to cytochrome c~ in an antimycininsensitive way, forming on the other hand a ubisemiquinol species acting as the reductant for cytochromes b [5]. According to these models, antimycin inhibits steady-state electron transport to cytochrome c by the be1 complex because it prevents