Agrawal V P, Stumpf P K
Arch Biochem Biophys. 1985 Jul;240(1):154-65. doi: 10.1016/0003-9861(85)90018-9.
Microsomes prepared from leek epidermal tissue readily elongate stearoyl-CoA to very long chain fatty acid with malonyl-CoA as the C2 unit. In the absence of stearoyl-CoA, but in the presence of ATP, microsomes elongate endogenous free fatty acids. Endogenous CoA is the source of CoA. Palmitoyl, stearoyl, and higher saturated acyl-CoAs are readily elongated by the microsomal system but oleoyl-CoA is ineffective; however, the higher monounsaturated acyl-CoAs can be elongated. Since the very long chain fatty acids of the leek epidermis are all saturated, it would appear that the reaction controlling the nature of the final acyl product is the inactivity of oleoyl-CoA as a substrate. There is no evidence that acyl carrier protein participates in the elongation reactions. Evidence is also presented suggesting that (a) there may be two elongation systems, one responsible for the conversion of stearoyl-CoA to arachidonyl-CoA and the second involved in the conversion of arachidonyl-CoA to very long chain fatty acids, and that (b) the elongation activities may be associated with a large polypeptide.
从韭菜表皮组织制备的微粒体能够轻易地将硬脂酰辅酶A延长为极长链脂肪酸，以丙二酰辅酶A作为C2单元。在没有硬脂酰辅酶A但存在ATP的情况下，微粒体能够延长内源性游离脂肪酸。内源性辅酶A是辅酶A的来源。棕榈酰、硬脂酰和更高的饱和酰基辅酶A很容易被微粒体系统延长，但油酰辅酶A无效；然而，更高的单不饱和酰基辅酶A可以被延长。由于韭菜表皮的极长链脂肪酸都是饱和的，看来控制最终酰基产物性质的反应是油酰辅酶A作为底物的无活性。没有证据表明酰基载体蛋白参与延长反应。也有证据表明：（a）可能存在两个延长系统，一个负责将硬脂酰辅酶A转化为花生四烯酰辅酶A，第二个参与将花生四烯酰辅酶A转化为极长链脂肪酸；以及（b）延长活性可能与一种大的多肽相关。
