Bacteriorhodopsin D85N: three spectroscopic species in equilibrium.
Bacteriorhodopsin D85N: three spectroscopic species in equilibrium.
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细菌视紫红质 D85N：三种光谱物种处于平衡状态。
DOI：
10.1021/bi00056a019
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发表时间：
1993
期刊：
影响因子：
2.9
通讯作者：
Stroud,RM
中科院分区：
文献类型：
--
作者：
Turner,GJ;Miercke,LJ;Thorgeirsson,TE;Kliger,DS;Betlach,MC;Stroud,RM
1992年11月17日收到的修订稿摘要：基态吸光度测量表明，含天冬酰胺的盐生盐杆菌第85位氨基酸残基(D85N)的BR在平衡状态下以三种不同的发色状态存在。在pH 6-12范围内，这三个态的吸收光谱与构成野生型BR光循环的后半部分的闪光诱导光谱中间体相似。其中一种状态在405 nm处有最大吸收，具有去质子化的Schiff碱，主要含有13-顺式视网膜，证明它是BR光循环中M中间体的紧密同系物。其他物种具有最大吸光度，与野生型N(570 Nm)和O(615 Nm)光中间体的最大吸光度相对应。O型的视网膜成分以全反式异构体为主。平衡物种浓度的pH依赖关系与光中间体、N和O的pH依赖关系密切。这些数据支持强调细菌视紫红质光循环中反向反应的作用的动力学模型。D85N基态平衡的能量和光谱特征支持将其用作解释BR光周期后期分子跃迁的模型。细菌视紫红质(BR)1是在嗜盐古细菌盐生盐杆菌中发现的最丰富的视网膜结合蛋白。这七个跨膜家族的成员作为光驱动的质子泵发挥作用(Oester helt&Stoeckenius，1973)，以产生支持需要能量的细胞过程的膜电位(Danon&Stoeckenius，1974)。光循环是由光吸收启动的，光吸收刺激BR进入激发状态，该激发状态通过一系列不同的光学中间体进行热衰减。中间体之间的转化与质子转移反应相耦合(Stoeckenius&Bogomolni，1982；Lanyi，1992；Oester helt等人，1992；Rothschild，1992)。为了理解BR中光介导的质子转移的分子机制，需要阐明在BR光循环过程中出现的功能相关的分子态的数目和结构，以及调节这些状态之间转换的化学和物理因素。通过对野生型BR和含有单一氨基酸取代基的变异型BR蛋白之间的光循环中间体之间的光学跃迁进行动力学建模，提高了对这一机制的理解(Varo&Lanyi，1990a；Thorgeirsson等人，1991；Lozier等人，1992)。
Revised Manuscript Received November 17, 1992 abstract: Ground-state absorbance measurements show that BR from Halobacterium halobium containing asparagine at residue 85 (D85N) exists as three distinct chromophoric states in equilibrium. In the pH range 6-12 theabsorbance spectra of the three states are demonstrated to be similar to flash-induced spectral intermediates which comprise the latter portion of the wild-type BR photocycle. One of the states absorbs maximally at 405 nm, has a deprotonated Schiff base, and contains predominantly the 13-cis form of retinal, identifying it as a close homologue of the M intermediate in the BR photocycle. The other species possess absorbance maxima with correspondence to those of the wild-type N (570 nm) and O (615 nm) photointermediates. The retinal composition of the O-like form was found to be dominated by all-trans isomer. The pH dependence of the concentrations of the equilibrium species correspondsclosely with the pH dependence of the, N, and O photointermediates. These data support kinetic models which emphasize the role of back-reactions during the photocycle of bacteriorhodopsin. Energetic and spectral characterization of the D85N ground-state equilibrium supports its use as a model for elucidating molecular transitions comprising the latter portion of the BR photocycle.Bacteriorhodopsin (BR) 1 is the most abundant retinal binding protein found in the salt-loving Archaebacterium Halobacterium halobium. This member of the seven transmembrane spanning family functions as a light-driven proton pump (Oesterhelt & Stoeckenius, 1973) to generate a membrane potential which supports energy-requiring cellular processes (Danon & Stoeckenius, 1974). The photocycle is initiated by light absorption which stimulates BR into an excited state that thermally decays through a series of optically distinct intermediates. The conversions between intermediates are coupled to proton-transfer reactions (Stoeckenius & Bogomolni, 1982; Lanyi, 1992; Oesterhelt et al., 1992; Rothschild, 1992). The number and structures of functionally relevant molecular states which occur during the BR pho-tocycle and the chemical and physical factors which regulate the transitions between these states need to be elucidated to understand the molecular mechanism of light-mediated proton translocation in BR. Understanding of this mechanism has been advanced by kinetic modeling of optical transitions between photocycle intermediates observed for wild-type BR and variant BR proteins containing single amino acid sub-stitutions (Varo & Lanyi, 1990a; Thorgeirsson et al., 1991; Lozier et al., 1992).
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影响因子：
2.9
作者：
P. Scherrer;M. Mathew;W. Sperling;W. Stoeckenius
通讯作者：
P. Scherrer;M. Mathew;W. Sperling;W. Stoeckenius
DOI：
10.1073/pnas.85.12.4148
发表时间：
1988-06-01
影响因子：
11.1
作者：
MOGI, T;STERN, LJ;KHORANA, HG
通讯作者：
KHORANA, HG
影响因子：
16.6
作者：
W. Stoeckenius;R. Bogomolni
通讯作者：
W. Stoeckenius;R. Bogomolni
影响因子：
2.9
作者：
BRAIMAN, MS;MOGI, T;ROTHSCHILD, KJ
通讯作者：
ROTHSCHILD, KJ
天冬氨酸 96 和 85 在细菌视紫红质作为质子泵的功能中发挥着核心作用。
影响因子：
11.4
作者：
Hans;K. Fendler;Ernst Bamberg;J. Tittor;Dieter Oesterhelt
通讯作者：
Dieter Oesterhelt