Edgerton M E, Moore T A, Greenwood C
Biochem J. 1980 Sep 1;189(3):413-20. doi: 10.1042/bj1890413.
The formation and reversal of the acid species of purple membrane generated below pH 4.00 (22 degrees C) is studied together with the photochemical cycle over the pH range 6.40--3.20. The buffering capacity of the membrane reaches a peak at pH 4.30, indicating the possibility of a conformational change taking place. The generation of the new spectral species can take place in the dark and is unaffected by the addition of reducing agents. Kinetic parameters measured indicate that the group being titrated below pH 4.00 could be the same as that protonated in the formation of intermediate O. The temporal placement of intermediate O after M in the photochemical cycle is shown to be incompatible with the data presented here. Reneutralization of acidified purple membrane shows that the spectral changes in acid are reversible but the phototransient properties are altered.
研究了在pH 4.00（22℃）以下产生的紫膜酸性物种的形成与逆转，以及在pH 6.40 - 3.20范围内的光化学循环。膜的缓冲能力在pH 4.30时达到峰值，表明可能发生了构象变化。新光谱物种的产生可以在黑暗中发生，并且不受还原剂添加的影响。所测量的动力学参数表明，在pH 4.00以下被滴定的基团可能与在中间体O形成过程中被质子化的基团相同。光化学循环中中间体O在M之后的时间位置与这里给出的数据不相符。酸化紫膜的再中和表明，酸性条件下的光谱变化是可逆的，但光瞬态性质发生了改变。
