Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
Photochem Photobiol. 2012 Jan-Feb;88(1):90-7. doi: 10.1111/j.1751-1097.2011.01011.x. Epub 2011 Nov 17.
Microbial rhodopsins are an important class of light-activated transmembrane proteins whose function is typically studied on bulk samples. Herein, we apply photochromic fluorescence resonance energy transfer to investigate the dynamics of these proteins with sensitivity approaching the single-molecule limit. The brightness of a covalently linked organic fluorophore is modulated by changes in the absorption spectrum of the endogenous retinal chromophore that occur as the molecule undergoes a light-activated photocycle. We studied the photocycles of blue-absorbing proteorhodopsin and sensory rhodopsin II (SRII). Clusters of 2-3 molecules of SRII clearly showed a light-induced photocycle. Single molecules of SRII showed a photocycle upon signal averaging over several illumination cycles.
微生物视紫红质是一类重要的光激活跨膜蛋白,其功能通常在批量样品上进行研究。在此,我们应用光致变色荧光共振能量转移来研究这些蛋白质的动力学,其灵敏度接近单分子极限。通过光激活光循环过程中内源性视黄醛发色团吸收光谱的变化来调节共价连接的有机荧光团的亮度。我们研究了蓝光吸收蛋白视紫红质和感觉视紫红质 II(SRII)的光循环。2-3 个 SRII 分子簇明显显示出光诱导的光循环。通过对几个光照循环的信号平均化,单个 SRII 分子表现出光循环。