An engineered form of iso-1-cytochrome c with lysine 73 mutated to histidine is shown to increase by nearly 500-fold the rate of a conformational gate that modulates the rate of electron transfer into this protein. This result demonstrates the potential of protein engineering to provide electron transfer gates with tailored properties. The pH dependence of the rate of the conformational electro...

Yeast iso-1-cytochrome c covalently modified at cysteine-102 with (4-bromomethyl-4'-methylbipyridine)[bis(bipyridine)]Ru2+ (Ru-102-Cyt c) has been used as a photoactive electron donor to mitochondrial cytochrome c oxidase (COX) reconstituted into phospholipid vesicles. Rapid kinetics of membrane potential generation by the enzyme following flash-induced photoreduction of Ru-102-Cyt c heme has b...

The transfer of electrons from the pyridine nucleotide-linked dehydrogenases to cytochrome c is mediated by a class of enzymes which has been termed the cytochrome c reductases (1). Two TPNH cytochrome c reductases, both flavoproteins, have been purified, one by Haas et al. (1) from yeast, and another by Horecker (2) from liver.’ Analogous enzymes in the case of DPNH have been implicated in par...

In previous papers, the cytochrome absorption spectra of some sporogenic yeasts were reported by Fiol and Claisse (10) in the genus Kluyveromyces, Fiol and Hmama (11) in the genus Ambrosiozyma, Hormoascus and Hyphopichia, Fiol and Claisse (12) in the genus Pichia, and in some Candida Montrocher and Claisse (14, 15). We have now examined the cytochrome absorption spectra of the nitratenegative y...

The complete amino acid sequence of the cytochrome c from the flight muscles of a saturnid moth, Samia Cynthia, has been established. This protein is functionally and structurally homologous to other mammalian-type cytochromes c. However, it differs from cytochromes c of vertebrate origin by having a nonacetylated NHz-terminal residue, being 107 rather than 104 residues long and carrying an arg...

Inhibitor titrations using antimycin have been used to study the pool behavior of ubiquinone and cytochrome c in the respiratory chain of the yeast Saccharomyces cerevisiae. If present in a homogeneous pool, these carriers should be able to diffuse freely through or along the membrane respectively and accept and subsequently donate electrons to an infinite number of the respective respiratory c...

Heme attachment to the apoforms of fungal mitochondrial cytochrome c and c1 requires the activity of cytochrome c and c1 heme lyases (CCHL and CC1HL), which are enzymes with distinct substrate specificity. However, the presence of a single heme lyase in higher eukaryotes is suggestive of broader substrate specificity. Here, we demonstrate that yeast CCHL is active toward the non-cognate substra...