Reorientations in the bacteriorhodopsin photocycle.
Reorientations in the bacteriorhodopsin photocycle.
复制标题
细菌视紫红质光循环中的重新定向。
作者：
Q. Song;Greg S. Harms;C. Wan;Carey K. Johnson
在盐盐杆菌的紫色膜悬浮液中发现了可逆的光诱导细菌视紫红质重新定向。通过时间分辨线性二色性和瞬态吸收测量，测量了细菌视紫红质在光循环纳秒到毫秒阶段的各向异性。从这些测量中，确定了K、L、M和O中间体的各向异性，并与初始选择的发色团取向有关。K态和L态的各向异性分别为0.38 +/- 0.01和0.35 +/- 0.01。进一步的各向异性衰减后，形成约0.5毫秒的中间体M是在这个阶段的定向运动的光循环的证据。O中间体的各向异性恒定，值为0.39 +/- 0.02，表明随着O态的形成，蛋白质的初始取向得到恢复。这些结果表明BR中的取向是光诱导的，并且是可逆的。对聚丙烯酰胺凝胶中紫色膜的L和M进行了类似的测量，其中L和M状态的各向异性分别为0.38 +/- 0.014和0.36 +/- 0.01。这些结果表明，固定在凝胶中的BR也会发生取向改变。凝胶中未检测到M中间体形成后M态的各向异性衰减，与悬浮液中的M中间体相反。紫色膜悬浮液中的BR在K态、K—b> L阶段、M态（可能与M1—b> M2过渡有关）和O态（几乎完全恢复到原始取向）中观察到取向变化。（摘要删节250字）
Reversible photoinduced reorientations of bacteriorhodopsin have been detected in suspensions of the purple membrane of Halobacterium salinarium. The anisotropy in bacteriorhodopsin during the nanosecond through millisecond stages of the photocycle was measured by time-resolved linear dichroism and transient absorption measurements. From these measurements the anisotropies of the K, L, M, and O intermediates were determined and related to the chromophore orientation with respect to the initially selected orientation. The anisotropies of the K and L states are 0.38 +/- 0.01 and 0.35 +/- 0.01, respectively. Further anisotropy decay after formation of the M intermediate in about 0.5 ms is evidence of orientational motion at this stage in the photocycle. A constant anisotropy with a value of 0.39 +/- 0.02 in the O intermediate demonstrates a recovery of the initial protein orientation with the formation of the O state. These results demonstrate that reorientations in BR are photoinduced and reversible. Similar measurements for L and M were carried out for purple membrane in polyacrylamide gels, where the anisotropies in the L and M states are 0.38 +/- 0.014 and 0.36 +/- 0.01, respectively. These results show that reorientations also occur in BR immobilized in gels. Anisotropy decay in the M state after formation of the M intermediate was not detected in the gels, in contrast to the M intermediate in suspensions. Orientational changes are observed for BR in purple membrane suspensions in the K state, during the K-->L step, in the M state possibly related to an M1-->M2 transition, and in the O state, where an almost complete return to the original orientation occurs.(ABSTRACT TRUNCATED AT 250 WORDS)
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使用改变光循环的突变体研究羟胺与细菌视紫红质的反应：不同光中间体的选择性反应性。
DOI：
10.1073/pnas.88.6.2583
发表时间：
1991
影响因子：
11.1
作者：
Subramaniam,S;Marti,T;Rösselet,SJ;Rothschild,KJ;Khorana,HG
通讯作者：
Khorana,HG
影响因子：
2.9
作者：
BRAIMAN, MS;MOGI, T;ROTHSCHILD, KJ
通讯作者：
ROTHSCHILD, KJ
影响因子：
3.4
作者：
Nagle,JF
通讯作者：
Nagle,JF
DOI：
10.1073/pnas.86.23.9228
发表时间：
1989-12-01
影响因子：
11.1
作者：
OTTO, H;MARTI, T;HEYN, MP
通讯作者：
HEYN, MP
影响因子：
5.6
作者：
HENDERSON, R;BALDWIN, JM;DOWNING, KH
通讯作者：
DOWNING, KH