Wavelength dependent cis-trans isomerization in vision
Wavelength dependent cis-trans isomerization in vision
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DOI：
10.1021/bi0116137
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发表时间：
2001-11-20
期刊：
影响因子：
2.9
通讯作者：
Mathies, RA
中科院分区：
文献类型：
--
作者：
Kim, JE;Tauber, MJ;Mathies, RA
视觉中的主要事件是g蛋白偶联受体视紫质中11-顺式视网膜发色团的光驱动顺式-反式异构化。早期的测量表明，这种光异构化的反应量子产率近似于0.67 [Dartnall (1936) Proc. R. Soc]。A 156, 158-170；Dartnall (1968) Vision Res. 8, 339-358]并提出量子产率与波长无关[Schneider (1939) Proc. Natl.]。学会科学。[j].美国，170,102-112。在这里，我们更准确地确定了phi(500) = 0.65 +/- 0.01，并揭示了令人惊讶的phi取决于入射光的波长。虽然450 nm和480 nm之间的量子产率没有差异，但当光子能量降低到20,000 cm(-1) （500 nm）以下时，量子产率显著下降。在测量的最红波长（570 nm），量子产率相对于500 nm值降低了5 +/- 1%。这些实验纠正了长期以来的假设，即视觉中的量子产率与波长无关，并支持了200fs引发视觉的光异构反应是由非稳态激发态振动波包动力学决定的假设。
The primary event in vision is the light-driven cis-trans isomerization of the 11-cis-retinal chromophore in the G-protein coupled receptor rhodopsin. Early measurements showed that this photoisomerization has a reaction quantum yield phi of similar to0.67 [Dartnall (1936) Proc. R. Soc. A 156, 158-170; Dartnall (1968) Vision Res. 8, 339-358] and suggested that the quantum yield was wavelength independent [Schneider (1939) Proc. Natl. Acad. Sci. U.S.A. 170, 102-112]. Here we more accurately determine phi (500) = 0.65 +/- 0.01 and reveal that phi surprisingly depends on the wavelength of the incident light. Although there is no difference in the quantum yield between 450 and 480 nm, the quantum yield falls significantly as the photon energy is reduced below 20 000 cm(-1) (500 nm). At the reddest wavelength measured (570 nm), the quantum yield is reduced by 5 +/- 1% relative to the 500 nm value. These experiments correct the long-held presumption that the quantum yield in vision is wavelength independent, and support the hypothesis that the 200 fs photoisomerization reaction that initiates vision is dictated by nonstationary excited-state vibrational wave packet dynamics.