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Abstract
Low-temperature difference spectra of gradient-purified mitochondria from Sterigmatomyces halophilus revealed the presence of a-, b- and c-type cytochromes, spectrally similar to those of other yeasts. Fourth-order finite difference analysis resolved the broad a-band of b-and c-type cytochromes into eight peaks. Absorption maxima at about 539, 543·5 and 547·5 nm were attributed to one, or perhaps two, cytochrome(s) c that are loosely bound to the mitochondrial membrane. Cytochrome c 1 was identified at 5505 to 5515 nm. Maxima at about 554, 556, 559 and 562 nm were attributed to three or four distinct b-type cytochromes on the basis of their differential reduction by NADH, dithionite, or ascorbate plus N, N,-N′, N′,-tetramethyl-p-phenylenediamine in the absence or presence of antimycin. Difference spectra in the presence of CO or cyanide indicated the presence of cytochromes a (600 nm) and a 3 (608 nm). Finite difference analysis of the cytochromes c oxidase peak centred at 600 nm revealed two components; the major component at 600 nm was identified as cytochrome a and the minor component at 605 nm as cytochrome a 3 . A further CO-binding haemoprotein was tentatively identified as cytochrome o.
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