LIEBMAN P A
Biophys J. 1962 Mar;2(2 Pt 1):161-78. doi: 10.1016/s0006-3495(62)86847-7.
Three spectral entities have been observed in single intact frog rod outer segments at 506 mmu, 480 mmu and 380 mmu. It is likely that the peak of 506 mmu was somewhat altered by bleaching reactions and originated at about 510 mmu. This is identified with the 502 mmu frog rhodopsin of digitonin extracts. Spectra in polarized light have the same maximum, identifying the dichroism of rods with rhodopsin. The dichroic ratio is around 6, giving the outer segment an axial density of 0.09/5mu or 0.9 OD total, with a pigment concentration of 2 to 3 mM. The dichroism data are used to compute the angle separating the rhodopsin molecular absorption vectors in rods from perfect restriction to a plane. This angle is 16 degrees or 23 degrees depending on which of two assumptions one chooses for the type of molecular ordering. The spectral peaks at 480 mmu and 380 mmu are thought to correspond respectively to metarhodopsin and retinene. Disappearance of the former is accompanied by accumulation of the latter. This reaction seems to occur more slowly in the intact outer segment than the corresponding reaction in solution. Spread of bleaching spectra from illuminated to dark areas of the same rod did not occur over distances of 2 mu or greater. Spectra were similar from rod to rod and from point to point on the same rod showing that frog rods are spectrally homogeneous both individually and collectively.
在完整的单个青蛙视杆细胞外段中观察到了三个光谱实体，其波长分别为506毫微米、480毫微米和380毫微米。506毫微米处的峰值可能因漂白反应而有所改变，其原本大约在510毫微米处。这与洋地黄皂苷提取物中502毫微米的青蛙视紫红质相对应。偏振光下的光谱具有相同的最大值，这表明视杆细胞的二向色性与视紫红质有关。二向色性比率约为6，这使得视杆细胞外段的轴向密度为0.09/5微米或总吸光度为0.9 OD，色素浓度为2至3毫摩尔。利用二向色性数据来计算视杆细胞中视紫红质分子吸收矢量与完全限制在一个平面内时的夹角。根据对分子排列类型所做的两种假设中的一种，这个角度为16度或23度。480毫微米和380毫微米处的光谱峰值分别被认为对应于变视紫红质和视黄醛。前者的消失伴随着后者的积累。在完整的视杆细胞外段中，这个反应似乎比在溶液中的相应反应发生得更慢。漂白光谱在同一视杆细胞的光照区域和黑暗区域之间的传播在2微米或更大的距离上并未发生。不同视杆细胞之间以及同一视杆细胞上不同点之间的光谱相似，这表明青蛙视杆细胞在个体和总体上在光谱上都是均匀的。
