Rothschild K J, Gillespie J, DeGrip W J
Biophys J. 1987 Feb;51(2):345-50. doi: 10.1016/S0006-3495(87)83341-6.
Fourier transform infrared difference spectroscopy (FTIR) reveals that the Meta II intermediate of the rhodopsin bleaching cascade is structurally distorted relative to rhodopsin. In addition to previously detected alterations in the state of carboxyl groups, a small part of the protein back-bone undergoes a conversion from alpha-helical to beta-type structure. All of these changes partially reverse during Meta II decay. This evidence together with FTIR studies of earlier photointermediates indicates that of the known photointermediates the protein structure of Meta II is the most distorted. It is concluded that light causes rhodopsin to convert into a conformationally distorted form (Meta II), which subsequently refolds into a more rhodopsin-like conformation (opsin).
傅里叶变换红外差光谱法（FTIR）显示，视紫红质漂白级联反应的中间体Meta II在结构上相对于视紫红质发生了扭曲。除了之前检测到的羧基状态变化外，一小部分蛋白质主链从α螺旋结构转变为β型结构。所有这些变化在Meta II衰变过程中部分逆转。这一证据以及对早期光中间体的FTIR研究表明，在已知的光中间体中，Meta II的蛋白质结构扭曲程度最大。得出的结论是，光导致视紫红质转变为构象扭曲的形式（Meta II），随后再折叠成更类似视紫红质的构象（视蛋白）。
