National Institutes of Health, Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, Bethesda, MD 20892, USA.
Appl Spectrosc. 2013 Jan;67(1):73-85. doi: 10.1366/12-06662.
We recently published procedures describing the isolation of absolute infrared spectra for the intermediates of the bacteriorhodopsin (BR) photocycle and from these, obtaining transitional difference spectra between consecutive intermediates. In that work, we concentrated mainly on proton-binding centers and the route of proton transport across the membrane. In the current study, we used isolated spectra for the amide I, amide II, and amide III envelopes to obtain quantitative information on the extent of conformational change accompanying each transition in the photocycle. Our main finding was that most of the conformational changes occur in the conversion of the M(F) intermediate to N. In our earlier publication, a new proton acceptor, absorbing at 1650 cm(-1) was identified, which appeared to accept a proton from Asp96COOH during the transformation of BR† to L. Below, we present evidence that supports this interpretation and propose a possible role for this new component.
我们最近发表了描述细菌视紫红质（BR）光循环中间产物的绝对红外光谱分离方法的论文，并从这些光谱中获得了连续中间产物之间的跃迁差光谱。在这项工作中，我们主要集中在质子结合中心和质子跨膜运输的途径上。在当前的研究中，我们使用分离的酰胺 I、酰胺 II 和酰胺 III 包络线来获得定量信息，了解光循环中每个跃迁伴随的构象变化程度。我们的主要发现是，大多数构象变化发生在 M(F)中间产物向 N 的转化过程中。在我们之前的出版物中，我们确定了一个新的质子受体，在 1650cm(-1)处吸收，它似乎在 BR†向 L 的转化过程中从 Asp96COOH 接受一个质子。下面，我们提出了支持这种解释的证据，并提出了这个新成分的可能作用。
