Whitcomb R W, Sangha J S, Schneyer A L, Crowley W F
Reproductive Endocrine Unit, Massachusetts General Hospital, Boston 02114.
Clin Chem. 1988 Oct;34(10):2022-5.
Any exploration of the physiology of secretion of free alpha subunit of glycoprotein hormones in humans requires a sensitive assay system that shows low cross reactivity with the intact hormones (lutropin, follitropin, thyrotropin, and choriogonadotropin). We established and validated such an assay system with a monoclonal antibody for detection of free alpha subunit in serum with better sensitivity (detection limit, 30 ng/L) and less cross reactivity (0.67% with intact human lutropin) than with available polyclonal antibody methods. Thus, the specific epitope recognized by this antibody apparently is exposed only on the free or uncombined form of alpha subunit and is concealed after non-covalent combination with any beta subunit. Using Western blot analysis, we show that most of the cross reactivity is probably the result of contamination of the human lutropin standard (obtained from the National Hormone and Pituitary Program, NIH) with small amounts of free alpha subunit. With such a specific and sensitive method, it should be possible to obtain more-precise information regarding the secretion of free alpha subunit.
对人类糖蛋白激素游离α亚基分泌生理学的任何探索都需要一个灵敏的检测系统，该系统与完整激素（促黄体生成素、促卵泡生成素、促甲状腺激素和绒毛膜促性腺激素）的交叉反应性较低。我们建立并验证了这样一种检测系统，该系统使用一种单克隆抗体来检测血清中的游离α亚基，与现有的多克隆抗体方法相比，具有更高的灵敏度（检测限为30 ng/L）和更低的交叉反应性（与完整的人促黄体生成素的交叉反应性为0.67%）。因此，该抗体识别的特定表位显然仅在α亚基的游离或未结合形式上暴露，在与任何β亚基非共价结合后被掩盖。通过蛋白质印迹分析，我们表明大部分交叉反应性可能是由于人促黄体生成素标准品（从美国国立卫生研究院国家激素和垂体项目获得）被少量游离α亚基污染所致。有了这样一种特异且灵敏的方法，应该能够获得关于游离α亚基分泌的更精确信息。
