Vibrational Coupling between Helices Influences the Amide I Infrared Absorption of Proteins: Application to Bacteriorhodopsin and Rhodopsin
Vibrational Coupling between Helices Influences the Amide I Infrared Absorption of Proteins: Application to Bacteriorhodopsin and Rhodopsin
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DOI：
10.1021/jp300329k
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发表时间：
2012-04-19
影响因子：
3.3
通讯作者：
Barth, Andreas
中科院分区：
文献类型：
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作者：
Karjalainen, Eeva-Liisa;Barth, Andreas
使用跃迁偶极耦合（TDC）模拟螺旋蛋白片段多聚体的酰胺1光谱，用于单个酰胺振荡器之间的远程相互作用和来自二肽的DFT数据（la Cour Jansen等人，J. Chem. Phys. 2006，125，44312）用于最近邻相互作用。不同螺旋上酰胺基团之间的振动耦合使螺旋吸收向更高的波数移动。对于10埃距离的螺旋二聚体（1 cm（-1）），这种效应很小，并且仅受到螺旋之间相对取向变化的适度影响。然而，当膜蛋白中有几个螺旋捆绑在一起时，这种影响就变得相当大了。特别的例子是7-螺旋膜蛋白细菌视紫红质（BR）和视紫红质，其中由于BR单体内的螺旋间偶联，上移分别为4.3和5.3 cm（-1）。当BR单体与三聚体结合时，发生4.0 cm（-1）的进一步上移。我们提出，螺旋间的振动耦合解释了实验观察到的异常高波数的酰胺I带的BR
The amide 1 spectrum of multimers of helical protein segments was simulated using transition dipole coupling (TDC) for long-range interactions between individual amide oscillators and DFT data from dipeptides (la Cour Jansen et al. J. Chem. Phys. 2006, 125, 44312) for nearest neighbor interactions. Vibrational coupling between amide groups on different helices shift the helix absorption to higher wavenumbers. This effect is small for helix dimers (1 cm(-1)) at 10 angstrom distance and only moderately affected by changes in the relative orientation between the helices. However, the effect becomes considerable when several helices are bundled in membrane proteins. Particular examples are the 7-helix membrane proteins bacteriorhodopsin (BR) and rhodopsin, where the upshift is 4.3 and 5.3 cm(-1) respectively, due to interhelical coupling within a BR monomer. A further upshift of 4.0 cm(-1) occurs when BR monomers associate to trimers. We propose that interhelical vibrational coupling explains the experimentally observed unusually high wavenumber of the amide I band of BR