VIBRATIONAL SPECTROSCOPY OF BACTERIORHODOPSIN MUTANTS - LIGHT-DRIVEN PROTON TRANSPORT INVOLVES PROTONATION CHANGES OF ASPARTIC-ACID RESIDUE-85, RESIDUE-96, AND RESIDUE-212
VIBRATIONAL SPECTROSCOPY OF BACTERIORHODOPSIN MUTANTS - LIGHT-DRIVEN PROTON TRANSPORT INVOLVES PROTONATION CHANGES OF ASPARTIC-ACID RESIDUE-85, RESIDUE-96, AND RESIDUE-212
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DOI：
10.1021/bi00423a002
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发表时间：
1988-11-15
期刊：
影响因子：
2.9
通讯作者：
ROTHSCHILD, KJ
中科院分区：
文献类型：
--
作者：
BRAIMAN, MS;MOGI, T;ROTHSCHILD, KJ
为Br .FWDARW获得了傅立叶变换红外（FTIR）差异光谱。 k，br .fwdarw。 l和br .fwdarw。在细菌近红紫红素突变体中的M光反应，其中ASP残基85、96、115和212被ASN和胶水代替。这些突变体中先前归因于同位素标记的ASP COOH基团的差异峰。通常，在四个残基之一中，每个COOH峰都会受到突变的强烈影响。因此，可以将每个峰暂时分配给特定的ASP。从这些分配中，得出了BR的质子泵送机理的模型，该模型具有ASP -85，-96和-212之间的质子转移，发色团Schiff碱和其他可离子化基团。该模型可以解释BR光光中间体的FTIR差异光谱中观察到的COOH峰，还可以解释BR的位置导向突变体的其他最新结果。
Fourier transform infrared (FTIR) difference spectra have been obtained for the bR .fwdarw. K, bR .fwdarw. L, and bR .fwdarw. M photoreactions in bacteriorhodopsin mutants in which Asp residues 85, 96, 115, and 212 have been replaced by Asn and by Glue. Difference peaks that had previously been attributed to Asp COOH groups on the basis of isotopic labeling were absent or shifted in these mutants. In general, each COOH peak was affected strongly by mutation at only one of the four residues. Thus, it was possible to assign each peak tentatively to a particular Asp. From these assignments, model for the proton-pumping mechanism of bR is derived, which features proton transfers among Asp-85, -96, and -212, the chromophore Schiff base, and other ionizable groups within the protein. The model can explain the observed COOH peaks in the FTIR difference spectra of bR photointermediates and could also account for other recent results on site-directed mutants of bR.