SUMMARY: The properties of cells and mitochondria isolated from , a hydrocarbon-utilizing yeast, grown on ethanol, glucose and -alkanes were examined. A comparative study was made of the properties of the whole cells and mitochondria of and of those of .

The reduced-minus-oxidized cytochrome spectrum of grown on ethanol showed a much larger amount of cytochromes and a very broad cytochrome -type absorption band compared with . The relative amounts of cytochromes in on hydrocarbons differed according to the growth phase but never reached the levels obsered in the cells grown on ethanol. Furthermore, as judged by the reduced-minus-oxidized cytochrome spectra, was much less affected by glucose repression than was . The fatty acids of mitochondria isolated from ethanol-grown consisted mainly of equal amounts of oleic (C) and linoleic (C) unsaturated fatty acids, each making up about 40% of the total. In contrast, mitochondria contained palmitoleic (C) (approx. 45%) and oleic (approx. 35%) as the main fatty-acid components. There was an increase in the amount of oleic acid (60%) relative to linoleic acid (20%) when was grown on even-numbered hydrocarbons and a progressive increase in the amount of heptadecenoic acid (C) up to 75% when grown on odd-numbered -alkanes of increasing carbon-chain length from C to C. The changes in fatty-acid composition were correlated with changes in membrane fluidity as measured by differences in transition temperatures in Arrhenius plots of mitochordrial membrane-bound enzymes.

The ATPases of and mitochondria were examined, and marked differences in specific activity (3- to 5-fold higher in ), pH profile and oligomycin sensitivity were noted.


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