Damodaran Srinivasan
Department of Food Science, University of Wisconsin-Madison, 1605 Linden Drive, Madison, WI 53706, USA.
Anal Bioanal Chem. 2003 May;376(2):182-8. doi: 10.1007/s00216-003-1873-6. Epub 2003 Apr 5.
A new circular dichroism (CD) spectroscopy technique for studying conformational changes in proteins in situ at the air-water interface is described. By using this technique, conformations of four proteins, viz., beta-casein, bovine serum albumin (BSA), lysozyme, and fibrinogen in the adsorbed state at the air-water interface have been studied. beta-Casein, which is predominantly in a disordered state in solution, assumes a beta-sheet conformation at the air-water interface. On the other hand, lysozyme and fibrinogen, which are alpha+beta-type proteins in solution, become beta-type proteins by completely transforming their alpha-helix structure into beta-sheets. Bovine serum albumin, which is an alpha-type protein in solution, loses its alpha-helix and becomes a disordered protein at the air-water interface. The results indicated that during unfolding and film formation at the interface, structural changes in proteins, regardless of their initial native state, follow the course of increasing beta-sheet and disordered structure and decreasing alpha-helix content. Although this seems to be the general trend, the exceptional case of BSA suggests, however, that this is not universal.
描述了一种用于原位研究蛋白质在空气 - 水界面构象变化的新型圆二色光谱（CD）技术。通过使用该技术，研究了四种蛋白质，即β-酪蛋白、牛血清白蛋白（BSA）、溶菌酶和纤维蛋白原在空气 - 水界面吸附状态下的构象。β-酪蛋白在溶液中主要处于无序状态，在空气 - 水界面呈现β-折叠构象。另一方面，溶菌酶和纤维蛋白原在溶液中是α + β型蛋白质，通过将其α-螺旋结构完全转化为β-折叠而变成β型蛋白质。牛血清白蛋白在溶液中是α型蛋白质，在空气 - 水界面失去其α-螺旋并变成无序蛋白质。结果表明，在界面处的展开和膜形成过程中，无论蛋白质的初始天然状态如何，其结构变化都遵循β-折叠和无序结构增加以及α-螺旋含量减少的过程。尽管这似乎是一般趋势，但BSA的特殊情况表明，这并非普遍适用。
