Bramley T A, Menzies G S, Williams R J, Kinsman O S, Adams D J
Department of Obstetrics and Gynaecology, University of Edinburgh.
J Endocrinol. 1991 Jan;128(1):139-51. doi: 10.1677/joe.0.1280139.
We have shown previously that partially purified human chorionic gonadotrophin (hCG) preparations inhibited the specific binding of 125I-labelled hLH or hCG to Candida albicans membranes at much lower concentrations than did highly purified hLH or hCG preparations. We now describe the characterization and partial purification of a heat-labile glycoprotein from commercially available gonadotrophin preparations. The factor strongly inhibited LH binding to Candida membranes, but not to sheep or pig luteal LH receptors. This material had a molecular weight of 16,000-21,000 daltons, bound strongly to CM-Sepharose at physiological pH, and could be resolved completely from hCG and from epidermal growth factor-like factors present in commercial gonadotrophin preparations. Its activity was not attenuated by a range of inhibitors specific for the four major classes of proteolytic enzymes, nor did it inhibit hormone binding by causing degradation of 125I-labelled hLH or hCG tracers. Factors which inhibited hLH binding to Candida membranes were also present in partially purified human urinary and equine serum gonadotrophin preparations and in placental extracts, but were not detected in highly purified CG of hLH preparations. The properties of this factor were similar to those described for beta-core protein, a cleavage product of the beta subunit of hCG which is a contaminant of commercial gonadotrophin preparations. Highly purified beta-core protein inhibited 125I-labelled hLH binding to Candida membranes, but not to sheep luteal binding sites. Preparations of hCG depleted of inhibitor activity could stimulate adenylate cyclase activity in Candida membranes almost five fold. In contrast, partially purified inhibitor preparations strongly inhibited basal adenylate cyclase activity (to 18% of control levels). These observations suggest that endogenous LH-like factors, perhaps similar to beta-core proteins of hCG, may play a role in the regulation of morphogenesis in Candida species.
我们之前已经表明，部分纯化的人绒毛膜促性腺激素（hCG）制剂比高度纯化的hLH或hCG制剂以低得多的浓度抑制125I标记的hLH或hCG与白色念珠菌膜的特异性结合。我们现在描述从市售促性腺激素制剂中对一种热不稳定糖蛋白的特性鉴定和部分纯化。该因子强烈抑制LH与念珠菌膜的结合，但不抑制与绵羊或猪黄体LH受体的结合。这种物质的分子量为16,000 - 21,000道尔顿，在生理pH下与CM - 琼脂糖强烈结合，并且可以与hCG以及市售促性腺激素制剂中存在的表皮生长因子样因子完全分离。其活性不会被一系列针对四大类蛋白水解酶的抑制剂减弱，也不会通过导致125I标记的hLH或hCG示踪剂降解来抑制激素结合。抑制hLH与念珠菌膜结合的因子也存在于部分纯化的人尿和马血清促性腺激素制剂以及胎盘提取物中，但在高度纯化的hLH制剂的CG中未检测到。该因子的特性与β - 核心蛋白描述的特性相似，β - 核心蛋白是hCGβ亚基的裂解产物，是市售促性腺激素制剂的污染物。高度纯化的β - 核心蛋白抑制125I标记的hLH与念珠菌膜的结合，但不抑制与绵羊黄体结合位点的结合。去除抑制剂活性的hCG制剂可以刺激念珠菌膜中的腺苷酸环化酶活性增加近五倍。相比之下，部分纯化的抑制剂制剂强烈抑制基础腺苷酸环化酶活性（至对照水平的18%）。这些观察结果表明，内源性LH样因子，可能类似于hCG的β - 核心蛋白，可能在念珠菌属形态发生的调节中起作用。
