Martyn P, Smith D L, Adams J B
School of Biochemistry, University of New South Wales, Sydney, Australia.
Mol Cell Endocrinol. 1988 Nov;60(1):7-13. doi: 10.1016/0303-7207(88)90114-1.
The properties of the enzyme catalyzing the formation of non-polar derivatives of estradiol-17 beta (E2) esterified to long-chain fatty acids have been investigated in microsomal preparations from bovine placenta cotyledons. A rapid enzyme assay has been developed which involves simple solvent partitioning. The membrane-bound enzyme showed a pH optimum of 5.0 and addition of fatty acyl-coenzymes A (CoAs), such as oleoyl-CoA, palmitoyl-CoA and palmitoleoyl-CoA, increased [3H]E2-fatty acyl ester formation from [3H]E2 by some 7-fold. Linoleoyl-CoA, linolenoyl-CoA and arachidonoyl-CoA were much less effective as acyl donors. Only 17 beta-fatty acyl monoesters were synthesized in each instance. Similar results were obtained with microsomes or mitochondria from bovine endometrium. The apparent Km for E2 employing placenta microsomes was 8.0 +/- 2.2 (SD) microM. Steroids such as testosterone, dehydroepiandrosterone and 5-androstene-3 beta, 17 beta-diol acted as competitive inhibitors (Ki values 79, 46 and 39 microM, respectively). These, and other data to be reported separately, which showed that these steroids were substrates for the enzyme, demonstrate that the latter is not specific for E2. The [3H]E2-fatty acyl ester fractions biosynthesized from [3H]E2 and bovine placental or endometrial tissue were analyzed by high pressure liquid chromatography (HPLC) and were found to have similar compositions characterized by a high percentage of unsaturated fatty acids.
在取自牛胎盘子叶的微粒体制剂中，对催化17β-雌二醇（E2）与长链脂肪酸酯化形成非极性衍生物的酶的特性进行了研究。已开发出一种快速酶测定法，该方法涉及简单的溶剂分配。膜结合酶的最适pH为5.0，添加脂肪酰辅酶A（CoA），如油酰辅酶A、棕榈酰辅酶A和棕榈油酰辅酶A，可使[3H]E2-脂肪酰酯从[3H]E2的形成增加约7倍。亚油酰辅酶A、亚麻酸辅酶A和花生四烯酰辅酶A作为酰基供体的效果要差得多。在每种情况下仅合成17β-脂肪酰单酯。用牛子宫内膜的微粒体或线粒体也得到了类似的结果。使用胎盘微粒体时，E2的表观Km为8.0±2.2（标准差）微摩尔。睾酮、脱氢表雄酮和5-雄烯-3β，17β-二醇等类固醇作为竞争性抑制剂（Ki值分别为79、46和39微摩尔）。这些以及其他将另行报道的数据表明这些类固醇是该酶的底物，证明该酶对E2不具有特异性。通过高压液相色谱（HPLC）分析了由[3H]E2和牛胎盘或子宫内膜组织生物合成的[3H]E2-脂肪酰酯馏分，发现它们具有相似的组成，其特征是不饱和脂肪酸的百分比很高。
