Protein flexibility and conformational state: a comparison of collective vibrational modes of wild-type and D96N bacteriorhodopsin.
Protein flexibility and conformational state: a comparison of collective vibrational modes of wild-type and D96N bacteriorhodopsin.
复制标题
DOI：
10.1016/s0006-3495(03)74562-7
复制
发表时间：
2003-08
影响因子：
3.4
通讯作者：
S. Whitmire;D. Wolpert;A. Markelz;J. Hillebrecht;J. Galan;R. Birge
中科院分区：
文献类型：
--
作者：
S. Whitmire;D. Wolpert;A. Markelz;J. Hillebrecht;J. Galan;R. Birge
利用太赫兹时域光谱对野生型（WT）和D96N突变型细菌紫质薄膜进行了远红外（FIR）光谱测量，作为水合作用、温度和构象状态的函数。结果与利用CHARMM进行正态分析得到的计算光谱进行了比较。我们发现FIR吸光度随频率缓慢增加，并且在2-60cm−1范围内无强窄特征，分辨率高达0.17cm−1。随着温度的降低，宽吸收的频率发生变化，具有强烈的非调和势，与中子非弹性散射结果一致。水合作用的减少使吸收转向更高的频率，这可能是由于内部水分子介导的耦合作用减少所致。基态的FIR吸光度几乎具有相同的频率依赖性，突变体的光密度小于WT。在M状态下，WT的FIR吸光度增加，而D96N则没有变化。这些结果代表了第一次测量FIR吸光度变化作为构象状态的函数。
Far infrared (FIR) spectral measurements of wild-type (WT) and D96N mutant bacteriorhodopsin thin films have been carried out using terahertz time domain spectroscopy as a function of hydration, temperature, and conformational state. The results are compared to calculated spectra generated via normal mode analyses using CHARMM. We find that the FIR absorbance is slowly increasing with frequency and without strong narrow features over the range of 2–60cm−1and up to a resolution of 0.17cm−1. The broad absorption shifts in frequency with decreasing temperature as expected with a strongly anharmonic potential and in agreement with neutron inelastic scattering results. Decreasing hydration shifts the absorption to higher frequencies, possibly resulting from decreased coupling mediated by the interior water molecules. Ground-state FIR absorbances have nearly identical frequency dependence, with the mutant having less optical density than the WT. In the M state, the FIR absorbance of the WT increases whereas there is no change for D96N. These results represent the first measurement of FIR absorbance change as a function of conformational state.