Ide K, Nishimura R, Mochizuki M
Department of Obstetrics and Gynecology, Kobe University School of Medicine.
Nihon Sanka Fujinka Gakkai Zasshi. 1987 Dec;39(12):2105-12.
Free alpha subunit (PU alpha) was extracted and purified from the urine of normal term pregnant women, and examined for molecular weight, electric charge, affinity to lectins (ConA, RCA and PNA) and the ability to combine with hCG beta in comparison with hCG alpha dissociated from hCG in vitro. The molecular weight of PU alpha was greater than that of hCG alpha in gel chromatography, but smaller in SDS-PAGE. However the free alpha subunits from the urine of patients with cancer were estimated to be larger than those of hCG alpha by both methods. In isoelectric focusing, while hCG alpha exhibited a neutral charge, PU alpha exhibited a negative charge. After treatment with sialidase, both hCG alpha and PU alpha were shifted to the basic region, indicating that they contained terminal sialic acid residues. The affinity to lectins indicated that PU alpha may contain both asparagine-linked and O-linked oligosaccharides, while hCG alpha contains asparagine-linked oligosaccharide only. PU alpha scarcely showed any combining activity with hCG beta, whereas hCG alpha combined actively. The O-linked oligosaccharide, which is not present in hCG alpha, may cause PU alpha to fail to combine with hCG beta.
从足月正常孕妇尿液中提取并纯化游离α亚基（PUα），并与体外从人绒毛膜促性腺激素（hCG）解离出的hCGα相比较，检测其分子量、电荷、对凝集素（刀豆球蛋白A、蓖麻凝集素和花生凝集素）的亲和力以及与hCGβ结合的能力。在凝胶色谱法中，PUα的分子量大于hCGα，但在十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳（SDS - PAGE）中则较小。然而，通过这两种方法估计，癌症患者尿液中的游离α亚基比hCGα的更大。在等电聚焦中，hCGα呈中性电荷，而PUα呈负电荷。用唾液酸酶处理后，hCGα和PUα均向碱性区域移动，表明它们含有末端唾液酸残基。对凝集素的亲和力表明，PUα可能同时含有天冬酰胺连接型和O连接型寡糖，而hCGα仅含有天冬酰胺连接型寡糖。PUα几乎不显示与hCGβ的任何结合活性，而hCGα则能积极结合。hCGα中不存在的O连接型寡糖可能导致PUα无法与hCGβ结合。
