Elucidation of the primary structures of the cytochromes c from several species of mammals (l-5), tuna fish (6), chicken (3), and yeast (7) has provided considerable insight into the evolution of cytochrome c and the structural features which may potentiate its biological activity. These topics and further implications of the knowledge derived from study of the comparative structures of cytochr...

The effect of 16 different genes (rad) conferring radiation sensitivity on chemically induced reversion in the yeast Saccharomyces cerevisiae was determined. The site of reversion used was a well-defined chain initiation mutant mapping in the structural gene coding for iso-1-cytochrome c. High doses of EMS and HNO(2) resulted in decreased reversion of cyc1-131 in rad6, rad9 and rad15 strains co...

A cytochrome oxidase was purified 52-fold from membranes of alkalophilic Bacillus firmus RAB by extraction with Triton X-100, ion-exchange and hydroxyapatite chromatography, and gel filtration. On denaturing gels, the purified enzyme dissociated into two subunits of 56,000 and 40,000 Mr as well as a cytochrome c with an Mr of approximately 14,000. Heme contents calculated for an enzyme with a m...

Eukaryotic cytochrome c oxidases are complex oligomeric membrane proteins composed of subunit polypeptides encoded by both nuclear and mitochondrial genomes. While the mitochondrially encoded subunits are encoded by unique genes, some of the nuclear-encoded subunits are encoded by multigene families. The isoforms produced by these multigene families are tissue-specific and/or developmentally re...

Energy transduction in the cytochrome bc(1) complex is achieved by catalyzing opposite oxido-reduction reactions at two different quinone binding sites. We have determined the pre-steady state kinetics of cytochrome b and c(1) reduction at varying quinol/quinone ratios in the isolated yeast bc(1) complex to investigate the mechanisms that minimize inhibition of quinol oxidation at center P by r...