Hydrogen bonds of water and C==O groups coordinate long-range structural changes in the L photointermediate of bacteriorhodopsin.
Hydrogen bonds of water and C==O groups coordinate long-range structural changes in the L photointermediate of bacteriorhodopsin.
复制标题
水和 C==O 基团的氢键协调细菌视紫红质的 L 光中间体中的长程结构变化。
DOI：
10.1021/bi9524530
复制
发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Maeda,A
中科院分区：
文献类型：
--
作者：
Yamazaki,Y;Tuzi,S;Saito,H;Kandori,H;Needleman,R;Lanyi,JK;Maeda,A
光适应性细菌视紫红质的傅立叶变换红外光谱在1618 cm{sup-1}处显示出一个谱带，该谱带在L中间体形成时移动到1625 cm{sup-1}。根据它在[1-{sup 13}C]缬氨酸标记的细菌视紫红质中发生位移并在Val 149 {r_arrow}Met突变体中出现扰动的事实，将其归属于Val 149的肽C=O。BR{yields}L差异带的强度在Thr 46 {r_arrow}瓦尔突变体中降低，但通过Asp 96 {r_arrow}Asn的额外突变而恢复。这些强度变化与水分子的氢键变化密切相关，表明Val 49的肽C=O是水合的。由于Val 46的C=O和Asp 96的羧基C= O以及靠近Asp 85的水分子的扰动，这可能会出现在Thr 46 {r_arrow}瓦尔突变体中。相反地，假设在V49 A中缺失的两个甲基引起的空腔中的水分子可能在Asp 96 {r_arrow}Asn的突变体中受到影响。我们认为L中间体中的Schiff碱对Asp 85的扰动通过Asp 85-Val 49区域的水分子的氢键、Val 49的C=O、Val 49和Thr 46之间的氢键以及Thr 46和Asp 96之间的氢键传递到Asp 96。参考文献44篇，图6。
Fourier transform infrared spectra of light-adapted bacteriorhodopsin exhibit a band at 1618 cm{sup -1} that shifts to 1625 cm{sup -1} upon formation of the L intermediate. It is assigned to the peptide C=O of Val149 from the fact that it shifts in [1-{sup 13}C]valine-labeled bacteriorhodopsin and appears perturbed in the Val149{r_arrow}Met mutant. The intensity of the BR{yields}L difference band is reduced in the Thr46{r_arrow}Val mutant but restored by the additional mutation of Asp96{r_arrow}Asn. These intensity changes are closely correlated with the H-bonding change of water molecules, suggesting that the peptide C=O of Val49 is hydrated. This could arise in the Thr46{r_arrow}Val mutant because of perturbation of the C=O of Val46, and the carboxylic C=O of Asp96, as well as water molecules proximal to Asp85. Conversely, the water molecule assumed to be in the cavity that arises from the missing two methyl groups in V49A could be affected in the mutant of Asp96{r_arrow}Asn. We propose that the perturbation exerted on Asp85 by the Schiff base in the L intermediate is transmitted to Asp96 through H-bonding of water molecules in the Asp85-Val49 region, the C=O of Val49, H-bonding between Val49 and Thr46, and H-bonding between Thr46 and Asp96. 44 refs., 6 figs.