Ultrafast Energy Redistribution in Local Hydration Shells of Phospholipids: A Two-Dimensional Infrared Study
Ultrafast Energy Redistribution in Local Hydration Shells of Phospholipids: A Two-Dimensional Infrared Study
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DOI：
10.1021/jz3018978
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发表时间：
2012-12-06
影响因子：
5.7
通讯作者：
Elsaesser, Thomas
中科院分区：
文献类型：
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作者：
Costard, Rene;Greve, Christian;Elsaesser, Thomas
磷脂的结构和功能特性受到其水化壳动力学的强烈影响。在这里，我们表明，当地的水池小到三个水分子周围的极性头基在磷脂反胶束（二油酰磷脂酰胆碱，DOPC）作为有效的水槽振动弛豫过程中释放的多余能量。瞬态二维（2D）红外光谱的OH伸缩激发的H2O壳表现出亚皮秒的热水基态，其中多余的能量随机在低频模式的建设。的2D光谱的中心线斜率的分析揭示了能量耗散的动力学，是显着快于结构波动的水池和保持不变的中间水合水平之间的每个极性头基的三个和八个水分子。我们的研究结果表明，在生物分子系统中的有限的小水池是足够的，以消散多余的能量来自电子或振动激发的衰减。
Structural and functional properties of phospholipids are strongly influenced by dynamics of their hydration shells. Here, we show that local water pools as small as three water molecules around the polar headgroups in phospholipid reverse micelles (dioleoylphosphatidylcholine, DOPC) serve as efficient sinks of excess energy released during vibrational relaxation. Transient two-dimensional (2D) infrared spectra of OH stretching excitations of H2O shells demonstrate a subpicosecond buildup of a hot water ground state, in which excess energy is randomized in low-frequency modes. An analysis of center line slopes of the 2D spectra reveals kinetics of energy dissipation that are significantly faster than structural fluctuations of the water pool and remain unchanged at intermediate hydration levels between three and eight water molecules per polar headgroup. Our results suggest that confined small water pools in biomolecular systems are sufficient to dissipate excess energy originating from the decay of electronic or vibrational excitations.