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首页> 外文期刊>Biophysical Chemistry: An International Journal Devoted to the Physical Chemistry of Biological Phenomena >SITE DIRECTED SPIN LABELING STUDIES OF STRUCTURE AND DYNAMICS IN BACTERIORHODOPSIN
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SITE DIRECTED SPIN LABELING STUDIES OF STRUCTURE AND DYNAMICS IN BACTERIORHODOPSIN

机译：细菌视紫红质的结构和动力学的现场定向自旋标记研究

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Site-directed spin labeling of membrane proteins has been used to determine: (1) the topography of the polypeptide chain with respect to the membrane/solution interface, and (2) the identity and orientation of secondary structure in selected regions. These features are deduced from the collision rates of nitroxide side chains with paramagnetic reagents in solution, and the principles of the method are reviewed with reference to bacteriorhodopsin. The dynamics of the nitroxide side chains relative to the backbone reveal tertiary interactions of the labeled site, and provide a promising means of time-resolving conformational changes. This aspect is illustrated by recent studies of structural changes in bacteriorhodopsin during the photocycle. In these experiments, nitroxide side chains were introduced at residues 72, 101 and 105 after replacement of the original residues by cysteine. Upon flash photolysis, the electron paramagnetic resonance spectrum of a nitroxide at 101, but not those at 72 or 105, is time-dependent. The spectral change develops during the decay of the M-intermediate, and reverses upon return to the ground state. The results suggest a movement of the C-D or E-F interhelical loops during the protonation changes of aspartate 96. [References: 24]
机译：膜蛋白的定点自旋标记已用于确定：（1）多肽链相对于膜/溶液界面的形貌，以及（2）选定区域中二级结构的身份和方向。这些特征是由氮氧化物侧链与溶液中顺磁性试剂的碰撞速率推导而来的，该方法的原理参考细菌视紫红质进行了综述。相对于主链的一氧化氮侧链的动力学揭示了标记位点的三级相互作用，并提供了一种有希望的时间分辨构象变化的方法。这方面的最新研究是光循环过程中细菌视紫红质结构变化的研究。在这些实验中，在用半胱氨酸替换原始残基后，在残基72、101和105处引入了氮氧化物侧链。在快速光解时，在101处而不是在72或105处的一氧化氮的电子顺磁共振光谱是时间依赖性的。光谱变化在M中间体衰变期间发展，并在返回基态时反转。结果表明天冬氨酸96质子化过程中C-D或E-F螺旋间的运动。[参考文献：24]

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