Lanyi Janos K, Balashov Sergei P
Department of Physiology and Biophysics, University of California, Irvine, CA 92697, USA.
Biochim Biophys Acta. 2008 Jul-Aug;1777(7-8):684-8. doi: 10.1016/j.bbabio.2008.05.005. Epub 2008 May 16.
Xanthorhodopsin is a light-driven proton pump like bacteriorhodopsin, but made more effective for collecting light by its second chromophore, salinixanthin, a carotenoid. Action spectra for transport and fluorescence of the retinal upon excitation of the carotenoid indicate that the carotenoid functions as an antenna to the retinal. The calculated center-to-center distance and angle of the transition moments of the two chromophores are 11 A and 56 degrees , respectively. As expected from their proximity, the carotenoid and the retinal closely interact: tight binding of the carotenoid, as indicated by its sharpened vibration bands and intense induced circular dichroism in the visible, is removed by hydrolysis of the retinal Schiff base, and restored upon reconstitution with retinal. This antenna system, simpler than photosynthetic complexes, is well-suited to study features of excited-state energy migration.
黄视紫红质是一种像细菌视紫红质一样的光驱动质子泵,但因其第二个发色团——类胡萝卜素盐藻黄质而更有效地收集光线。在类胡萝卜素激发时,视网膜转运和荧光的作用光谱表明类胡萝卜素起着视网膜天线的作用。计算得出的两个发色团中心到中心的距离和跃迁矩的角度分别为11埃和56度。正如从它们的接近程度所预期的那样,类胡萝卜素和视网膜紧密相互作用:类胡萝卜素的紧密结合表现为其振动带变锐以及在可见光区强烈的诱导圆二色性,这种结合在视网膜席夫碱水解后被消除,并在与视网膜重组后恢复。这个比光合复合物更简单的天线系统非常适合研究激发态能量迁移的特征。