Ultrafast spectroscopy of the visual pigment rhodopsin.
Ultrafast spectroscopy of the visual pigment rhodopsin.
复制标题
视色素视紫红质的超快光谱。
DOI：
10.1073/pnas.88.21.9809
复制
发表时间：
1991
影响因子：
11.1
通讯作者：
Callender,RH
中科院分区：
文献类型：
--
作者：
Yan,M;Manor,D;Weng,G;Chao,H;Rothberg,L;Jedju,TM;Alfano,RR;Callender,RH
我们报告了室温下亚皮秒分辨率的牛视觉色素视紫红质的时间分辨吸收研究。我们的数据显示，视紫红质（视紫红质的早期光产物）在 3.0 +/- 0.7 ps 内通过光化学形成。数据表明，红视紫红质的形成在动力学上先于沿视紫红质至红视紫红质反应坐标的两个物种。第一个是垂直激发的弗兰克-康登态。它以大约 200 fs 的寿命衰减为中间体，然后在 3.0 ps 内衰减为红视紫红质。我们将此中间体指定为沿着视紫红质发色团的 11-12 扭转坐标接近 90 度的激发态瞬态。视紫质的可交换质子与氘核的交换不会影响观察到的动力学。这些观察结果在定性和定量上都与分子动力学计算一致，分子动力学计算将视紫红质到红视紫红质的光转变建模为沿视紫红质发色团 11-12 扭转坐标的顺反异构化。
We report on time-resolved absorption studies of the bovine visual pigment rhodopsin with subpicosecond resolution at room temperature. Our data show that bathorhodopsin, rhodopsin's early photoproduct, is photochemically formed in 3.0 +/- 0.7 ps. The data suggest that bathorhodopsin formation is kinetically preceded by two species along the rhodopsin-to-bathorhodopsin reaction coordinate. The first is identified with the vertically excited Franck-Condon state. This decays with an approximately 200-fs lifetime to an intermediate, which then decays to bathorhodopsin in 3.0 ps. We assign this intermediate to be an excited state transient near 90 degrees along the 11-12 torsional coordinate of rhodopsin's chromophore. Exchange of rhodopsin's exchangeable protons for deuterons does not affect the observed dynamics. These observations are both qualitatively and quantitatively consistent with molecular dynamics calculations, which model the rhodopsin to bathorhodopsin phototransition as a cis-trans isomerization along the 11-12 torsional coordinate of rhodopsin's chromophore.