Skiba P J, Jackson L L
Department of Chemistry and Biochemistry, Montana State University, Bozeman 59717-0310.
Insect Biochem Mol Biol. 1994 Sep;24(8):847-53. doi: 10.1016/0965-1748(94)90113-9.
A fatty acid chain elongation process is involved in incorporation of saturated and unsaturated fatty acyl-CoA esters into 2-tridecanone and (Z)-10-heptadecen-2-one by Drosophila buzzatii. The microsomal fraction from mature male ejaculatory bulbs is chain-length specific and requires malonyl-CoA (or acetyl-CoA, if acetyl-CoA carboxylase were present) for the chain elongation step to 2-ketones. Decarboxylation of the proposed intermediate beta-ketoacid results in 2-ketone biosynthesis. Incubation of the microsomes with the acetyl-CoA carboxylase inhibitor avidin indicated that acetyl-CoA carboxylase was present in the microsomal preparations; however, washing of the microsomal preparation removed the acetyl-CoA carboxylase activity. Fatty acyl-CoA esters were also chain elongated to produce fatty acids two and four carbons longer, suggesting that the enzymes for normal fatty acid chain elongation are also present in the microsomal fraction from ejaculatory bulbs. How much, if any, of this fatty acid chain elongation system is used for 2-ketone biosynthesis is yet to be determined.
脂肪酸链延长过程参与了巴氏果蝇将饱和与不饱和脂肪酰辅酶A酯掺入2-十三烷酮和（Z）-10-十七碳烯-2-酮的过程。成熟雄性射精球的微粒体部分具有链长特异性，并且在链延长至2-酮的步骤中需要丙二酰辅酶A（如果存在乙酰辅酶A羧化酶，则需要乙酰辅酶A）。推测的中间β-酮酸脱羧导致2-酮的生物合成。用乙酰辅酶A羧化酶抑制剂抗生物素蛋白孵育微粒体表明，微粒体制剂中存在乙酰辅酶A羧化酶；然而，洗涤微粒体制剂会去除乙酰辅酶A羧化酶活性。脂肪酰辅酶A酯也会进行链延长，以产生长两个和四个碳原子的脂肪酸，这表明射精球微粒体部分中也存在正常脂肪酸链延长所需的酶。该脂肪酸链延长系统在多大程度上（如果有的话）用于2-酮的生物合成尚待确定。
