Tuckey R C, Stevenson P M
Biochim Biophys Acta. 1980 Jun 23;618(3):501-9. doi: 10.1016/0005-2760(80)90269-6.
Results from the assay of cholesteryl esterase (EC 3.1.1.13) with radiolabelled substrate are difficult to interpret if endogenous cholesteryl ester is present. We overcame this problem by using an isotope dilution method to measure the endogenous pool sizes of cholesteryl ester in subcellular fractions of the ovary. This permitted calculation of the total cholesteryl esterase activity of the mitochondrial microsomal, and cytosolic fractions of the ovary. At all stages of ovarian development most cholesteryl esterase acitivity was found in the cytosol, and generally there was more activity in the microsomes than the mitochondria. The cholesteryl esterase in all three fractions exhibited higher activity with cholesteryl oleate as substrate than with cholesteryl palmitate. Increases in cholesteryl esterase activity and endogenous ester concentration were found at two stages of ovarian development; firstly after initiation of follicular growth by gonadotropin in the immature ovary, and secondly during luteinization. The increases were observed in all three sub-cellular fractions. Administration of human choriogonadotropin to rats which possessed luteinized ovaries resulted in activation of the mitochondrial and microsomal cholesteryl esterase but not the cytosolic enzyme.
如果存在内源性胆固醇酯，用放射性标记底物测定胆固醇酯酶（EC 3.1.1.13）的结果就难以解释。我们通过使用同位素稀释法来测量卵巢亚细胞组分中胆固醇酯的内源性池大小，克服了这个问题。这使得能够计算卵巢线粒体、微粒体和胞质组分的总胆固醇酯酶活性。在卵巢发育的所有阶段，大部分胆固醇酯酶活性都存在于胞质溶胶中，并且一般来说，微粒体中的活性比线粒体中的更多。所有三个组分中的胆固醇酯酶以油酸胆固醇酯作为底物时比以棕榈酸胆固醇酯作为底物时表现出更高的活性。在卵巢发育的两个阶段发现胆固醇酯酶活性和内源性酯浓度增加；首先是在未成熟卵巢中促性腺激素启动卵泡生长后，其次是在黄体化期间。在所有三个亚细胞组分中都观察到了增加。给具有黄体化卵巢的大鼠注射人绒毛膜促性腺激素会导致线粒体和微粒体胆固醇酯酶的激活，但不会激活胞质酶。
