Dynamics of amide-I modes of the alanine dipeptide in D2O
Dynamics of amide-I modes of the alanine dipeptide in D2O
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DOI：
10.1021/jp0449511
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发表时间：
2005-04-14
影响因子：
3.3
通讯作者：
Hochstrasser, RM
中科院分区：
文献类型：
--
作者：
Kim, YS;Hochstrasser, RM
利用C-13同位素选择和二维红外光谱分别研究了丙氨酸二肽的乙酰基和氨基酰胺-1基团的平衡动力学。利用外差瞬变光栅法测量了酰胺跃迁的居群弛豫时间在500 fs范围内。在所有情况下，振动频率相关函数包括一个运动变窄的部分，一个接近800 fs的分量，以及一个代表在几ps时间尺度上静态结构分布的常数部分。中间时间尺度归因于羰基和水之间氢键的拉伸和弯曲的波动。
The equilibrium dynamics of the acetyl and amino amide-I groups of the alanine dipeptide were examined separately using C-13 isotopic selection and 2D IR. The population relaxation times of the amide transitions were measured to be in the range 500 fs by means of heterodyne transient grating methods. The vibrational frequency correlation functions consisted in all cases of a motionally narrowed part, a component near 800 fs, and a constant part representing a distribution of structures that is static on the few ps time scale. The intermediate time scale is attributed to fluctuations in the stretching and bending of hydrogen bonds between the carbonyl and water.