Institut für Biochemie und Molekularbiologie, ZBMZ, Freiburg, Germany.
Arch Biochem Biophys. 2010 Mar 15;495(2):159-64. doi: 10.1016/j.abb.2010.01.006. Epub 2010 Jan 13.
The exact nature of membrane protein folding and assembly is not understood in detail yet. Addition of SDS to a membrane protein dissolved in mild, non-polar detergent results in formation of mixed micelles and in subsequent denaturation of higher ordered membrane protein structures. The exact nature of this denaturation event is, however, enigmatic, and separation of an individual helix pair in mixed micelles has also not been reported yet. Here we followed unfolding of the human glycophorin A transmembrane helix dimer in mixed micelles by fluorescence spectroscopy. Energy transfer between differently labelled glycophorin A transmembrane helices decreased with increasing SDS mole fractions albeit without modifying the helicity of the peptides. The energetics and kinetics of the dimer dissociation in mixed micelles is analyzed and discussed, and the experimental data demonstrate that mixed micelles can be used as a general method to investigate unfolding of alpha-helical membrane proteins.
膜蛋白折叠和组装的确切性质尚未详细了解。将 SDS 添加到溶解在温和非极性洗涤剂中的膜蛋白中,会导致混合胶束的形成,并随后导致更高阶膜蛋白结构的变性。然而,这种变性事件的确切性质仍然是神秘的,并且在混合胶束中分离单个螺旋对也尚未报道。在这里,我们通过荧光光谱法研究了混合胶束中人类糖蛋白 A 跨膜螺旋二聚体的展开情况。尽管没有改变肽的螺旋性,但不同标记的糖蛋白 A 跨膜螺旋之间的能量转移随着 SDS 摩尔分数的增加而减少。分析和讨论了混合胶束中二聚体解离的能量学和动力学,实验数据表明混合胶束可用作研究α-螺旋膜蛋白展开的一般方法。