SIMULTANEOUS MONITORING OF LIGHT-INDUCED-CHANGES IN PROTEIN SIDE-GROUP PROTONATION, CHROMOPHORE ISOMERIZATION, AND BACKBONE MOTION OF BACTERIORHODOPSIN BY TIME-RESOLVED FOURIER-TRANSFORM INFRARED-SPECTROSCOPY
SIMULTANEOUS MONITORING OF LIGHT-INDUCED-CHANGES IN PROTEIN SIDE-GROUP PROTONATION, CHROMOPHORE ISOMERIZATION, AND BACKBONE MOTION OF BACTERIORHODOPSIN BY TIME-RESOLVED FOURIER-TRANSFORM INFRARED-SPECTROSCOPY
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DOI：
10.1073/pnas.87.24.9774
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发表时间：
1990-12-01
影响因子：
11.1
通讯作者：
HESS, B
中科院分区：
文献类型：
--
作者：
GERWERT, K;SOUVIGNIER, G;HESS, B
在光适应细菌视紫红质的光循环过程中，同时测量了红外和可见光谱范围内的吸光度变化，该光循环伴有矢量质子转移。整体拟合分析得出，对于生色团反应、蛋白质侧基的质子化变化以及主链运动，速率常数相同。由此结果我们得出结论：蛋白质不同部位的所有反应相互同步，不同部位不存在独立的循环。天冬氨酸 - 85的羰基振动（表明其质子化）出现的速率常数与席夫碱去质子化相同。天冬氨酸 - 96的羰基振动消失（很可能表明去质子化），其速率常数与席夫碱再质子化相同。这一结果支持了所提出的机制，即质子化的席夫碱、质子释放途径上的去质子化天冬氨酸（Asp - 85）以及质子摄取途径上的质子化天冬氨酸（Asp - 96）作为内部催化质子结合位点。
Absorbance changes in the infrared and visible spectral range were measured in parallel during the photocycle of light-adapted bacteriorhodopsin, which is accompanied by a vectorial proton transfer. A global fit analysis yielded the same rate constants for the chromophore reactions, for protonation changes of protein side groups, and for the backbone motion. From this result we conclude that all reactions in various parts of the protein are synchronized to each other and that no independent cycles exists for different parts. The carbonyl vibration of Asp-85, indicating its protonation, appears with the same rate constant as the Schiff base deprotonation. The carbonyl vibration of Asp-96 disappears, indicating most likely deprotonation, with the same rate constant as for the Schiff base reprotonation. This result supports the proposed mechanism in which the protonated Schiff base, a deprotonated aspartic acid (Asp-85) on the proton-release pathway, and a protonated aspartic acid (Asp-96) on the proton-uptake pathway act as internal catalytic proton-binding sites.