Watson K, Houghton R L, Bertoli E, Griffiths D E
Biochem J. 1975 Feb;146(2):409-16. doi: 10.1042/bj1460409.
The lipid composition of yeast cells was manipulated by the use of an unsaturated fatty acid auxotroph of Saccharomyces cerevisiae. There was a 2-3-fold decrease in the concentration of cytochromes a+a3 when the unsaturated fatty acid content of the cells was decreased from 60-70% of the total fatty acid to 20-30%. The amounts of cytochromes b and c were also decreased under these conditions, but to a lesser extent. Further lipid depletion, to proportions of less than 20% unsaturated fatty acid, led to a dramatic decrease in the content of all cytochromes, particularly cytochromes a+a3. The ATPase (adenosine triphosphatase), succinate oxidase and NADH oxidase activities of the isolated mitochondria also varied with the degree of unsaturation of the membrane lipids. The lower the percentage of unsaturated fatty acid, the lower was the enzymic activity. Inhibition of mitochondrial ATPase by oligomycin, on the other hand, was not markedly influenced by the membrane-lipid unsaturation. Npn-linear Arrenius plots of mitochondrial membrane-bound enzymes showed transition temperatures that were dependent on the degree of membrane-lipid unsaturation. The greater the degree of lipid unsaturation, the lower was the transition temperature. It was concluded that the degree of unsaturation of the membrane lipids plays an important role in determining the properties of mitochondrial membrane-bound enzymes.
通过使用酿酒酵母的不饱和脂肪酸营养缺陷型来操控酵母细胞的脂质组成。当细胞的不饱和脂肪酸含量从总脂肪酸的60 - 70%降至20 - 30%时，细胞色素a + a3的浓度下降了2 - 3倍。在这些条件下，细胞色素b和c的量也有所下降，但降幅较小。进一步减少脂质，使不饱和脂肪酸比例低于20%，导致所有细胞色素的含量急剧下降，尤其是细胞色素a + a3。分离出的线粒体的ATP酶（腺苷三磷酸酶）、琥珀酸氧化酶和NADH氧化酶活性也随膜脂质的不饱和程度而变化。不饱和脂肪酸的百分比越低，酶活性越低。另一方面，寡霉素对线粒体ATP酶的抑制作用并未受到膜脂质不饱和程度的显著影响。线粒体膜结合酶的非直线阿累尼乌斯图显示转变温度取决于膜脂质的不饱和程度。脂质不饱和程度越高，转变温度越低。得出的结论是，膜脂质的不饱和程度在决定线粒体膜结合酶的性质方面起着重要作用。
