Caticha O, Grover S, Yu W, Odell W D
Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City.
Endocr Res. 1994 Feb;20(1):21-37. doi: 10.3109/07435809409035853.
In this study, we characterize from Saccharomyces cerevisiae: 1) a protein that has immunological similarities to human chorionic gonadotropin (hCG), and 2) a binding site for this hCG-like protein which also binds hCG and human luteinizing hormone (hLH). Saccharomyces cerevisiae chorionic gonadotropin-like protein (ScCGLP) was purified in several steps. This protein when analyzed by SDS-PAGE, under nondenaturing conditions, produced two bands, one at 110-kDa, and another at 57.5-kDa. Under denaturing conditions, only the 57.5-kDa band appeared. This 57.5-kDa band also reacted in a Western blot, using a polyclonal antibody directed against hCG. Purified ScCGLP reacted in the following hCG immunoassays: 1) polyclonal rabbit anti-hCG equilibrium assay, 2) carboxyl-tail hCG equilibrium assay, 3) two equilibrium assays using monoclonal antibodies, and 4) free alpha-chain subunit equilibrium assay using a monoclonal antibody. Characterization of hCG/hLH binding sites in Saccharomyces cerevisiae was performed, and the ability of the ScCGLP to displace I125-hCG was also shown. Human CG and hLH were able to compete for I125-hCG binding to Saccharomyces cerevisiae blastospores (Kds of approximately 10(-8) M), while ScCGLP competed with higher affinity (Kd = 9.41 x 10(-10) M). The hCG-like immunoactivity was also present in Saccharomyces growth media, as well as in all brands of commercial beer studied.
在本研究中，我们对酿酒酵母进行了以下特性分析：1）一种与人类绒毛膜促性腺激素（hCG）具有免疫相似性的蛋白质；2）该hCG样蛋白的一个结合位点，此位点也能结合hCG和人类促黄体生成素（hLH）。酿酒酵母绒毛膜促性腺激素样蛋白（ScCGLP）经过多步纯化。该蛋白在非变性条件下通过SDS-PAGE分析时产生两条带，一条在110 kDa处，另一条在57.5 kDa处。在变性条件下，仅出现57.5 kDa的条带。这条57.5 kDa的条带在使用针对hCG的多克隆抗体进行的蛋白质印迹分析中也有反应。纯化后的ScCGLP在以下hCG免疫测定中表现出反应：1）兔抗hCG多克隆平衡测定；2）羧基末端hCG平衡测定；3）使用单克隆抗体的两种平衡测定；4）使用单克隆抗体的游离α链亚基平衡测定。对酿酒酵母中hCG/hLH结合位点进行了特性分析，并且还展示了ScCGLP取代I125-hCG的能力。人绒毛膜促性腺激素（hCG）和hLH能够竞争I125-hCG与酿酒酵母芽生孢子的结合（解离常数约为10^(-8) M），而ScCGLP以更高的亲和力竞争（解离常数Kd = 9.41×10^(-10) M）。hCG样免疫活性也存在于酿酒酵母生长培养基以及所研究的所有商业啤酒品牌中。
