Sherman W V, Slifkin M A, Caplan S R
Biochim Biophys Acta. 1976 Feb 16;423(2):238-48. doi: 10.1016/0005-2728(76)90182-1.
Aqueous suspensions of bacteriorhodopsin in purple membrane fragments from Halobacterium halobium have bben subjected to microsecond flash photometry utilizing both unpolarized and polarized light. Depletion of the ground state chromophore centered at 570 nm is accompanied by the formation of transients absorbing maximally at 410 nm and 660 nm with rise times of about 0.4 and 6 ms, respectively. Decay of both transients and reformation of the ground state chromophore occurs with identical first-order kinetics with a half life of about 6 ms. All three chromophores are polarized with dichroic ratios which remain constant throughout the transient lifetimes, indicating that Brownian rotation of the chromophore within the membrane is considerably restricted. Whereas agents which induce permeability of membranes to protons (2,4-dinitrophenol, carbonylcyanide-m-chlorophenylhydrazone) and non-specific univalent cations (gramicidin) or inhibit ATPase (ouabain) had no influence, the K+-specific ionophore valinomycin in the presence of K+ inhibited and quenched the formation of the 660 nm transient with concomitant increase in lifetime of the 410 nm transient and delay in recovery of the 570 nm chromophore. High concentrations of Na+ produced an effect similar to that of valinomycin. The relationship of these data to the mechanism of the proton pump in the intact bacterium is discussed, with the conclusion that the 410 nm transient performs a key role.
利用非偏振光和偏振光，对来自嗜盐菌紫膜片段中的细菌视紫红质水悬浮液进行了微秒级闪光光度测量。以570nm为中心的基态发色团的消耗伴随着分别在410nm和660nm处最大吸收的瞬态的形成，其上升时间分别约为0.4ms和6ms。两个瞬态的衰减以及基态发色团的重新形成以相同的一级动力学发生，半衰期约为6ms。所有三种发色团都具有偏振性，其二向色比在整个瞬态寿命期间保持恒定，这表明膜内发色团的布朗旋转受到相当大的限制。虽然诱导膜对质子（2,4-二硝基苯酚、羰基氰化物间氯苯腙）和非特异性单价阳离子（短杆菌肽）具有通透性或抑制ATP酶（哇巴因）的试剂没有影响，但在存在K+的情况下，K+特异性离子载体缬氨霉素抑制并淬灭了660nm瞬态的形成，同时410nm瞬态的寿命增加，570nm发色团的恢复延迟。高浓度的Na+产生了与缬氨霉素类似的效果。讨论了这些数据与完整细菌中质子泵机制的关系，得出结论：410nm瞬态起着关键作用。
