Adamski J, Sierralta W D, Jungblut P W
Max-Planck-Institut für experimentelle Endokrinologie, Hannover, FRG.
Acta Endocrinol (Copenh). 1989 Aug;121(2):161-7. doi: 10.1530/acta.0.1210161.
Homogenates of porcine endometrium contain substantial activity for the dehydrogenation of estradiol-17 beta but little for estrone reduction. Both activities are associated with cytoplasmic structures. The dehydrogenase is characterized by a pH 7.7 optimum, Km 2.2 x 10(-7) mol/l for estradiol and Km 4.4 x 10(-5) mol/l for the cosubstrate NAD+. The corresponding figures for the reductase are pH 6.6, Km 1.1 x 10(-6) mol/l for estrone and Km 2.1 x 10(-5) mol/l for the cosubstrate NADPH. The (mitochondrial/lysosomal) 17,000 x g particulate fraction contains a 52-fold higher dehydrogenase than reductase activity. The (microsomal) 200,000 x g particulate fraction is only 16-fold richer in dehydrogenase. Isopycnic centrifugations of the two fractions in Percoll gradients reveal that estrone reductase and the coequilibrating marker enzyme cytochrome c reductase occur in constant proportions, whereas the dehydrogenase/cytochrome c reductase ratios are different. Both, the kinetic data and the structural assignments speak in favour of individual enzymes catalyzing the dehydrogenation of estradiol and the reduction of estrone. All gradient fractions exhibiting dehydrogenase activity feature small, electrodense vesicles of 0.15-0.20 microns in diameter as a common structural element which might harbour the dehydrogenase.
猪子宫内膜匀浆具有大量使雌二醇 - 17β脱氢的活性，但使雌酮还原的活性很低。这两种活性都与细胞质结构相关。脱氢酶的特征是最适pH值为7.7，对雌二醇的Km值为2.2×10⁻⁷mol/L，对共底物NAD⁺的Km值为4.4×10⁻⁵mol/L。还原酶的相应数据为pH值6.6，对雌酮的Km值为1.1×10⁻⁶mol/L，对共底物NADPH的Km值为2.1×10⁻⁵mol/L。（线粒体/溶酶体）17,000×g的颗粒组分中脱氢酶活性比还原酶活性高52倍。（微粒体）200,000×g的颗粒组分中脱氢酶含量仅高16倍。在Percoll梯度中对这两个组分进行等密度离心显示，雌酮还原酶和共同平衡的标记酶细胞色素c还原酶以恒定比例出现，而脱氢酶/细胞色素c还原酶的比例不同。动力学数据和结构归属都表明存在催化雌二醇脱氢和雌酮还原的个别酶。所有表现出脱氢酶活性的梯度组分都有一个共同的结构元件，即直径为0.15 - 0.20微米的小的、电子致密的囊泡，脱氢酶可能存在于此。
