Environmental effects on formation and photoreaction of the M412 photoproduct of bacteriorhodopsin: implications for the mechanism of proton pumping.
Environmental effects on formation and photoreaction of the M412 photoproduct of bacteriorhodopsin: implications for the mechanism of proton pumping.
复制标题
环境对细菌视紫红质 M412 光产物形成和光反应的影响：对质子泵浦机制的影响。
DOI：
10.1021/bi00506a031
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发表时间：
1981
期刊：
影响因子：
2.9
通讯作者：
Korenstein,R
中科院分区：
文献类型：
--
作者：
Kalisky,O;Ottolenghi,M;Honig,B;Korenstein,R
Ofra Kalisky、Michael Ottolenghi、* Barry Honig、* 和 Rafi Korenstein 摘要：进行了光化学研究，研究了温度、pH 和脱水对光适应细菌视紫红质 (bR570) 光循环中 M412 中间体的形成和反向光反应的影响。在 40 至 90 C 范围内的连续光照实验表明，在低温下，在 L550 中间体阶段发生支化，其中母体颜料的逆反应与 M412 的形成竞争。在低温下，M412 的产率在高 pH 值下显着增加。该效果归因于pK_10的蛋白质组对L550-*M412过程的速率的催化作用。我们的结果与之前 L550-»M412 转变过程中酪氨酸去质子化的证据结合起来，表明酪氨酸离子的形成是席夫碱去质子化的先决条件。提出了一个模型，其中两者
Ofra Kalisky, Michael Ottolenghi,* Barry Honig,* and Rafi Korenstein abstract: Photochemical studies of the effects of temperature, pH, and dehydration on the formation and back photo-reaction of the M412 intermediate in the photocycle of light-adapted bacteriorhodopsin (bR570) are carried out. Continuous illumination experiments in the range between-40 and-90 C indicate that at low temperatures branching occurs at the stage of the L550 intermediate in which a back reaction to the parent pigment competes with the formation of M412. At low temperatures the yield of M412 is markedly increased at high pH. The effect is attributed tothe catalytic action of a protein group of pK— 10 on the rate of the L550-* M412 process. Our results, taken together with previous evidence for deprotonation of a tyrosine during the L550-» M412 transition, suggest that the formationof a tyrosinate ion is a prerequisite for depro-tonation of the Schiff base. A model is proposed in which both