Baselt D R, Fodor S P, van der Steen R, Lugtenburg J, Bogomolni R A, Mathies R A
Department of Chemistry, University of California, Berkeley 94720.
Biophys J. 1989 Jan;55(1):193-6. doi: 10.1016/S0006-3495(89)82791-2.
Halorhodopsin (HR) and sensory rhodopsin (SR) have been regenerated with retinal analogues that are covalently locked in the 6-s-cis or 6-s-trans conformations. Both pigments regenerate more completely with the locked 6-s-trans retinal and produce analogue pigments with absorption maxima (577 nm for HR and 592 nm for SR) nearly identical to those of the native pigments (577 and 587 nm). This indicates that HR and SR bind retinal in the 6-s-trans conformation. The opsin shift for the locked 6-s-trans analogue in HR is 1,200 cm-1 less than that for the native chromophore (5,400 cm-1). The opsin shift for the 6-s-trans analogue in SR is 1,100 cm-1 less than that for the native retinal (5,700 cm-1). This demonstrates that approximately 20% of the opsin shift in these pigments arises from a protein-induced change in the chromophore conformation from twisted 6-s-cis in solution to planar 6-s-trans in the protein. The reduced opsin shift observed for the locked 6-s-cis analogue pigments compared with the locked 6-s-trans pigments may be due to a positive electrostatic perturbation near C7.
嗜盐视紫红质（HR）和感官视紫红质（SR）已用共价锁定在6 - s - 顺式或6 - s - 反式构象的视黄醛类似物进行了再生。两种色素用锁定的6 - s - 反式视黄醛再生得更完全，并产生吸收最大值（HR为577 nm，SR为592 nm）与天然色素（577和587 nm）几乎相同的类似色素。这表明HR和SR以6 - s - 反式构象结合视黄醛。HR中锁定的6 - s - 反式类似物的视蛋白位移比天然发色团的视蛋白位移小1200 cm-1（5400 cm-1）。SR中6 - s - 反式类似物的视蛋白位移比天然视黄醛的视蛋白位移小1100 cm-1（5700 cm-1）。这表明这些色素中约20%的视蛋白位移源于蛋白质诱导的发色团构象从溶液中的扭曲6 - s - 顺式变为蛋白质中的平面6 - s - 反式。与锁定的6 - s - 反式色素相比，锁定的6 - s - 顺式类似色素观察到的视蛋白位移减少可能是由于C7附近的正静电扰动。
