Hydrogen Bond Dynamics of Histamine Monocation in Aqueous Solution: Car鈥揚arrinello Molecular Dynamics and Vibrational Spectroscopy Study

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• 作者：Jernej Stare ; Janez Mavri ; Joz虒e Grdadolnik ; Jernej Zidar ; Zvonimir B. Maksic虂 ; Robert Vianello
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：May 19, 2011
• 年：2011
• 卷：115
• 期：19
• 页码：5999-6010
• 全文大小：1163K
• 年卷期：v.115,no.19(May 19, 2011)
• ISSN：1520-5207

文摘

Hydration of histamine was examined by infrared spectroscopy and Car鈥揚arrinello molecular dynamics simulation. Histamine is a neurotransmitter and inflammation mediator, which at physiological pH conditions is present mainly in monocationic form. Our focus was on the part of vibrational spectra that corresponds to histamine N鈥揌 stretching, since these degrees of freedom are essential for its interactions with either water molecules or transporters and receptors. Assignment of the experimental spectra revealed a broad feature between 3350 and 2300 cm^鈥?, being centered at 2950 cm^鈥?, which includes a mixed contribution from the ring N鈥揌 and the aminoethyl N鈥揌 stretching vibrations. Computational analysis was performed in two ways: first, by making Fourier transformation on the autocorrelation function of all four N鈥揌 bond distances recorded during CPMD run, and second, and most importantly, by incorporating quantum effects through applying an a posteriori quantization of all N鈥揌 stretching motions utilizing our snapshot analysis of the fluctuating proton potential. The one-dimensional vibrational Schr枚dinger equation was solved numerically for each snapshot, and the N鈥揌 stretching envelopes were calculated as a superposition of the 0鈫? transitions. The agreement with the experiment was much better in the case of the second approach. Our calculations clearly demonstrated that the ring amino group absorbs at higher frequencies than the remaining three amino N鈥揌 protons of the protonated aminoethyl group, implying that the chemical bonding in the former group is stronger than in the three amino N鈥揌 bonds, thus forming weaker hydrogen bonding with the surrounding solvent molecules. In this way the results of the simulation complemented the experimental spectrum that cannot distinguish between the two sets of protons. The effects of deuteration were also considered. The resulting N鈥揇 absorption is narrower and red-shifted. The presented methodology is of general applicability to strongly correlated systems, and it is particularly tuned to provide computational support to vibrational spectroscopy. Perspectives are given for its future applications in computational studies of tunneling in enzyme reactive centers and for receptor activation.