Physiological Calcium Concentrations Slow Dynamics at the Lipid-Water Interface
Physiological Calcium Concentrations Slow Dynamics at the Lipid-Water Interface
复制标题
生理钙浓度导致脂水界面动力学缓慢
DOI：
10.1016/j.bpj.2018.08.044
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发表时间：
2018
影响因子：
3.4
通讯作者：
Baiz, Carlos R.
中科院分区：
文献类型：
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作者：
Valentine, Mason L.;Cardenas, Alfredo E.;Elber, Ron;Baiz, Carlos R.
磷脂可以在生理浓度下与离子强烈相互作用，并且这些相互作用可以改变膜特性。在这里，我们描述了钙离子对磷脂膜动力学的影响。我们使用的时间分辨超快二维红外（2D IR）光谱和分子动力学（MD）模拟相结合。我们发现，毫摩尔Ca 2+浓度导致在局部环境中的脂质-水界面的膜与磷脂酰丝氨酸的波动较慢。该效应仅在含有阴离子磷脂酰丝氨酸的双层中观察到;仅由两性离子磷脂酰胆碱组成的膜没有经历减速。使用酯基团作为无标记探针测量局部水动力学，并发现2.5 mM Ca 2+慢50%。MD模拟表明，Ca 2+主要与磷脂酰丝氨酸的羧酸基团结合。这些研究结果的影响，其中磷脂酰丝氨酸是暴露于细胞外钙，二价阳离子对脂质双层的生物物理效应的凋亡和病变细胞。
Phospholipids can interact strongly with ions at physiological concentrations, and these interactions can alter membrane properties. Here we describe the effects of calcium ions on the dynamics in phospholipid membranes. We used a combination of time-resolved ultrafast two-dimensional infrared (2D IR) spectroscopy and molecular dynamics (MD) simulations. We found that millimolar Ca2+concentrations lead to slower fluctuations in the local environment at the lipid-water interface of membranes with phosphatidylserine. The effect was only observed in bilayers containing anionic phosphatidylserine; membranes composed of only zwitterionic phosphatidylcholine did not experience a slowdown. Local water dynamics were measured using the ester groups as label-free probes and were found to be up to 50% slower with 2.5 mM Ca2+. MD simulations show that that Ca2+primarily binds to the carboxylate group of phosphatidylserines. These findings have implications for apoptotic and diseased cells in which phosphatidylserine is exposed to extracellular calcium, and for the biophysical effects of divalent cations on lipid bilayers.