Kubota S, Yeung H W, Yang J T
Biochim Biophys Acta. 1986 May 12;871(1):101-6. doi: 10.1016/0167-4838(86)90138-x.
The conformations of three abortifacient proteins, trichosanthin from the Chinese herb Tianhuafen and alpha- and beta-momorcharin from the Chinese herb Kuguazi, were studied by circular dichroism. Their spectra in the ultraviolet region (188-250 nm) were similar to each other and also pH-independent (between pH 5 and 9). All three proteins contained about 30% helix, as compared with 39% for trichosanthin by X-ray diffraction study, and 40-60% beta-sheets, but had no beta-turns, suggesting a structural homology among the proteins. The addition of 20 mM sodium dodecyl sulfate nearly doubled the helicity of beta-momorcharin at the expense of beta-sheets but had a small effect on the conformation of alpha-momorcharin, whereas the corresponding change in conformation for trichosanthin was in between the two momorcharins. This implies a marked difference in stability of the three proteins against the surfactant.
采用圆二色性研究了三种具有堕胎作用的蛋白质的构象，这三种蛋白质分别是来自中药天花粉的天花粉蛋白以及来自中药栝楼子的α-和β-苦瓜素。它们在紫外区域（188 - 250nm）的光谱彼此相似，并且也不依赖于pH值（pH值在5到9之间）。与通过X射线衍射研究得到的天花粉蛋白的39%螺旋结构相比，这三种蛋白质均含有约30%的螺旋结构，以及40 - 60%的β-折叠，但没有β-转角，表明这些蛋白质之间存在结构同源性。添加20mM十二烷基硫酸钠使β-苦瓜素的螺旋度几乎增加了一倍，代价是β-折叠减少，但对α-苦瓜素的构象影响较小，而天花粉蛋白构象的相应变化介于两种苦瓜素之间。这意味着这三种蛋白质对表面活性剂的稳定性存在显著差异。
