Michel-Villaz M, Roche C, Chabre M
Biophys J. 1982 Mar;37(3):603-16.
The orientational change of the absorbing dipole of the retinal chromophore in vertebrate rhodopsin (rhodo) upon photo-excitation to bathorhodopsin (batho), lumirhodopsin (lumi) and isorhodopsin (iso), has been studied by polarized absorption and linear dichroism measurements on magnetically oriented frog rod suspensions that were blocked at liquid nitrogen temperature. Both the azimuthal component delta theta and the polar component delta theta of the total angular change were studied in separate experiments. Delta theta was estimated from polarized absorption measurements on rods oriented transversally with respect to the analyzing beam. The data show unequivocally that upon the rhodo leads to batho transition, the dipole shifts out of the membrane plane by only few degrees; delta theta congruent to -3 degree. This azimuthal shift was nearly exactly reversed upon the batho leads to lumi decay. A very small shift (delta theta less than or equal to 1 degree) toward the membrane plane was observed upon a rhodo leads to iso conversion. The polar component delta theta of the angular shift was estimated by studying the photoreversion of linear dichroism induced by photo-excitation with polarized light in rods oriented parallel to the analyzing beam. Upon the rhodo leads to batho transition, ther was a shift delta theta = 11 +/- 3 degrees. The overall angular shift upon this first photo-exciting step, which corresponded to the isomerisation of retinal, was only delta omega = 11 +/- 3 degrees. This is smaller than what may be expected for a cis-trans isomerization of a retinal molecule with one end fixed, and different from what has been previously estimated by another group. These discrepancies are discussed.
通过对在液氮温度下被阻断的磁性取向青蛙视杆悬浮液进行偏振吸收和线性二色性测量，研究了脊椎动物视紫红质（视紫红质）中视网膜发色团吸收偶极子在光激发形成初生态视紫红质（初生态视紫红质）、发光视紫红质（发光视紫红质）和异视紫红质（异视紫红质）时的取向变化。在单独的实验中研究了总角度变化的方位角分量δθ和极角分量δθ。δθ是通过对相对于分析光束横向取向的视杆进行偏振吸收测量来估计的。数据明确显示，在视紫红质向初生态视紫红质转变时，偶极子仅从膜平面移出几度；δθ≈-3度。在初生态视紫红质向发光视紫红质衰减时，这种方位角偏移几乎完全反转。在视紫红质向异视紫红质转变时，观察到向膜平面有非常小的偏移（δθ≤1度）。通过研究在与分析光束平行取向的视杆中由偏振光光激发引起的线性二色性的光逆转，估计了角位移的极角分量δθ。在视紫红质向初生态视紫红质转变时，有一个δθ = 11±3度的偏移。在这第一步光激发步骤中，对应于视网膜异构化的总角位移仅为δω = 11±3度。这比一端固定的视网膜分子顺反异构化预期的值要小，并且与另一组先前估计的值不同。讨论了这些差异。
