Jammes H, de la Llosa-Hermier M P, de la Llosa P, Hermier C
Mol Cell Endocrinol. 1986 Sep;47(1-2):107-17. doi: 10.1016/0303-7207(86)90021-3.
The adenylate cyclase activation by ovine native LH, natural analogs (porcine LH, hCG) and chemical derivatives of LH (methylated, ethylated, isopropylated, guanidinated) was studied in purified plasma membranes of ovine corpora lutea, including the regulatory effects of guanyl 5'-yl imidophosphate (Gpp(NH)p) and Mg2+. The Ka app. for native LH (about 15 nM) was independent of Gpp(NH)p and Mg2+. Similar maximal activation of the enzyme was obtained by using ovine LH or natural analogs, but differences were remarked concerning the Ka app. values of these hormones. Porcine LH was equipotent with ovine LH; on the contrary, hCG exhibited a lower Ka app. value (3 nM). All chemical derivatives (Me-LH, Et-LH, Iso-LH and Gu-LH) exhibited Ka app. higher than native (about 2- to 4-fold), but similar maximal activation. No modification was observed in the regulatory effects of Gpp(NH)p and Mg2+ on the adenylate cyclase activation as a consequence of structural modifications of the hormone. A comparison of the steroidogenic activity on intact luteal cells and the adenylate cyclase activation ability on purified plasma membranes of the derivatives mentioned above evidenced some interesting discrepancies. The drop in adenylate cyclase activation potency of Me-LH was not reflected in its steroidogenic activity (Me-LH was equipotent with native LH); on the contrary, the capacity of Gu-LH to stimulate adenylate cyclase was not so much decreased as was its steroidogenic potency which was almost abolished.
在绵羊黄体的纯化质膜中，研究了绵羊天然促黄体生成素（LH）、天然类似物（猪LH、人绒毛膜促性腺激素[hCG]）以及LH的化学衍生物（甲基化、乙基化、异丙基化、胍基化）对腺苷酸环化酶的激活作用，包括5'-鸟苷酰亚胺二磷酸（Gpp(NH)p）和Mg2+的调节作用。天然LH的表观解离常数（Ka app.）（约15 nM）与Gpp(NH)p和Mg2+无关。使用绵羊LH或天然类似物可获得类似的酶最大激活，但这些激素的Ka app.值存在差异。猪LH与绵羊LH等效；相反，hCG的Ka app.值较低（3 nM）。所有化学衍生物（甲基化LH[Me-LH]、乙基化LH[Et-LH]、异丙基化LH[Iso-LH]和胍基化LH[Gu-LH]）的Ka app.均高于天然LH（约高2至4倍），但最大激活相似。由于激素结构修饰，未观察到Gpp(NH)p和Mg2+对腺苷酸环化酶激活的调节作用发生改变。对上述衍生物在完整黄体细胞上的类固醇生成活性和在纯化质膜上的腺苷酸环化酶激活能力进行比较，发现了一些有趣的差异。Me-LH的腺苷酸环化酶激活能力下降并未反映在其类固醇生成活性上（Me-LH与天然LH等效）；相反，Gu-LH刺激腺苷酸环化酶的能力下降幅度不如其类固醇生成能力大，后者几乎完全丧失。
