Plasma membrane from Candida tropicalis grown on glucose or hexadecane. II. Biochemical properties and substrate-induced alterations

Abstract

Isolated plasma membranes from the yeast Candida tropicalis grown on two different carbon sources (glucose or hexadecane), had similar contents of protein (60% of total dry weight), lipid (21–24%) and carbohydrates (16–21%). Sodium dodecyl sulphate gel electrophoresis of the membrane proteins revealed 17 and 19 protein bands, respectively, for glucose and hexadecane grown cells. There were marked differences in R F values and relative peak heights between the two gels. Sterols and free fatty acids were the major components of the plasma membrane lipids. Phospholipid content was less than 2% of total plasma membrane lipids. Membrane microviscosity, as determined by fluorescence polarization, was very high (16.6 P). Fatty acid determination of membrane lipids by gas chromatography showed a significant increase of C 16 fatty acids in plasma membranes of cells grown on hexadecane. Reduced-oxidized difference spectra demonstrated the presence of a b- type cytochrome in both Saccharomyces cerevisiae and C. tropicalis plasma membranes. Its concentration in C. tropicalis plasma membranes was three-fold greater in cells grown on hexadecane than in glucose grown cells.