Kaneda T, Smith E J
Can J Microbiol. 1980 Aug;26(8):893-8. doi: 10.1139/m80-155.
Fatty acid compositions of lipids from six bacteria and four yeasts were determined. Fatty acid de novo synthetases were investigated with respect to chain length specificity towards acyl-CoA primers of various chain lengths. Four species of bacteria (Bacillus subtilis, Corynebacterium cyclohexanicum, Micrococcus luteus, and Pseudomonas maltophilia) possess branched-chain fatty acids of the iso and anteiso series as the major acids. De novo synthetases from these organisms exhibited specificity towards the chain length of the primer in the order butyl-CoA > priopionyl-CoA > acetyl-CoA. The remainder, two bacteria and all four yeasts, have the straight-chain type of fatty acids only and fall into two groups: (1) Eschericia coli B, Pseudomonas fluorescens, and Saccharomyces cerevisiae, which utilize the primers in the order acetyl-CoA > priopionyl-CoA > butyryl-CoA; and (2) Candida sake, Candida tropicalis, and Rhodotorula glutinis, which show the order propionyl-CoA > acetyl-CoA > butyryl-CoA. L-alpha-Keto-beta-methylvalerate, a precursor of the branched-chain primers, can be used as a source of primer for fatty acid synthesis by the organisms with branched-chain acids but not by those with the straight-chain type. The results indicate that organisms having straight-chain fatty acids lack the branched-chain equivalents for two reasons: first, their enzymes are not active toward primers with more than three carbons, and second, they lack a system of supply suitable branched-chain primers. It appears that activities of de novo synthetases from the organisms having straight-chain fatty acids generally have much higher activities than those from the organisms possessing branched-chain fatty acids
测定了六种细菌和四种酵母脂质的脂肪酸组成。研究了脂肪酸从头合成酶对不同链长的酰基辅酶A引物的链长特异性。四种细菌（枯草芽孢杆菌、环己烷棒杆菌、藤黄微球菌和嗜麦芽窄食单胞菌）以异戊酸和anteiso系列的支链脂肪酸为主要脂肪酸。这些生物体的从头合成酶对引物链长的特异性顺序为丁酰辅酶A>丙酰辅酶A>乙酰辅酶A。其余的两种细菌和所有四种酵母仅具有直链型脂肪酸，并分为两组：（1）大肠杆菌B、荧光假单胞菌和酿酒酵母，它们按乙酰辅酶A>丙酰辅酶A>丁酰辅酶A的顺序利用引物；（2）清酒假丝酵母、热带假丝酵母和粘红酵母，它们的顺序为丙酰辅酶A>乙酰辅酶A>丁酰辅酶A。L-α-酮-β-甲基戊酸是支链引物的前体，可作为具有支链酸的生物体脂肪酸合成引物的来源，但不能作为具有直链型脂肪酸的生物体的引物来源。结果表明，具有直链脂肪酸的生物体缺乏支链脂肪酸有两个原因：第一，它们的酶对含碳数超过三个的引物无活性；第二，它们缺乏合适的支链引物供应系统。看来，具有直链脂肪酸的生物体的从头合成酶的活性通常比具有支链脂肪酸的生物体的活性高得多。
