Rosenheck K, Schneider A S
Proc Natl Acad Sci U S A. 1973 Dec;70(12):3458-62. doi: 10.1073/pnas.70.12.3458.
The circular dichroism spectra for proteins in situ in catecholamine secretory vesicles (chromaffin granules) is presented together with an analysis of protein conformation and turbidity effects on the spectra. The calculational analysis has resolved scattering and absorption effects in the turbid suspension spectra using a coated-sphere scattering model which allows for different materials in its shell and core. The intrinsic conformation of the proteins in situ was estimated by an iterative procedure with various trial protein conformations, for the chromaffin granules both intact and after release of their contents. The resulting average secondary structures (within about 10%) are: (25% alpha helix, 15% beta structure) for the membrane proteins and (15% alpha helix, 5% beta structure) for the soluble contents. The protein conformation did not change with osmotic release of the granule's contents. Consequently, if chromogranins are involved in a catecholamine storage complex, this is not reflected in any detectable change in their average secondary structure.
本文展示了儿茶酚胺分泌囊泡（嗜铬颗粒）中蛋白质原位的圆二色光谱，并对蛋白质构象以及光谱的浊度效应进行了分析。计算分析使用了一种涂层球体散射模型，解决了浑浊悬浮液光谱中的散射和吸收效应，该模型允许其壳层和核心中有不同的物质。通过对完整嗜铬颗粒及其内容物释放后的各种试验蛋白质构象进行迭代程序，估计了蛋白质原位的固有构象。所得的平均二级结构（误差约10%）为：膜蛋白（25%α螺旋，15%β结构），可溶性内容物（15%α螺旋，5%β结构）。颗粒内容物的渗透释放并未改变蛋白质构象。因此，如果嗜铬粒蛋白参与了儿茶酚胺储存复合体，这并未反映在其平均二级结构的任何可检测变化中。
