Jones R E, Plymate S R
Department of Medicine, Madigan Army Medical Center, Tacoma, Washington 98431.
Biol Reprod. 1988 Aug;39(1):76-80. doi: 10.1095/biolreprod39.1.76.
The effects of stearic (18:0), linolenic (18:3), and docosahexaenoic (22:6) acids on palmitoyl coenzyme A (CoA) formation by a long-chain fatty acid:CoASH ligase (adenosine monophosphate) (E. C. 6.2.1.3-enriched fraction from human spermatozoa were studied. Both 18:0 and 18:3 were competitive inhibitors for palmitic (16:0) acid activation with Kis of 17.7 and 5.7 microM, respectively. In contrast, 22:6 was a noncompetitive inhibitor demonstrating a Ki of 9.5 microM. These data coupled with previous studies support the conclusion that 16:0, 18:0, and 18:3 and other saturated and unsaturated fatty acids are activated by the same ligase enzyme in sperm. Although the kinetics and interactions of 22:6 are unique compared to the other fatty acids found in sperm phospholipids, we cannot discern from our data if it is activated by a separate enzyme. We propose that 22:6, or a metabolite of 22:6, may regulate free fatty acid utilization in human sperm and that this hypothesis may provide an enzymatic explanation for the changes observed in phospholipid-bound fatty acids during the epididymal maturation of sperm.
研究了硬脂酸（18:0）、亚麻酸（18:3）和二十二碳六烯酸（22:6）对人精子中长链脂肪酸：辅酶A连接酶（腺苷单磷酸）（E.C.6.2.1.3富集部分）催化棕榈酰辅酶A（CoA）形成的影响。18:0和18:3都是棕榈酸（16:0）激活的竞争性抑制剂，其抑制常数（Ki）分别为17.7和5.7微摩尔。相比之下，22:6是一种非竞争性抑制剂，Ki为9.5微摩尔。这些数据与先前的研究结果共同支持以下结论：16:0、18:0和18:3以及其他饱和和不饱和脂肪酸在精子中由同一种连接酶激活。尽管与精子磷脂中发现的其他脂肪酸相比，22:6的动力学和相互作用是独特的，但从我们的数据中无法判断它是否由一种单独的酶激活。我们提出，22:6或其代谢产物可能调节人精子中游离脂肪酸的利用，并且这一假设可能为精子在附睾成熟过程中磷脂结合脂肪酸的变化提供一种酶学解释。
