Schoch Rafael L, Haran Gilad, Brown Frank L H
Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA.
J Chem Phys. 2023 Jan 28;158(4):044112. doi: 10.1063/5.0129130.
Recent single-molecule measurements [Schoch et al., Proc. Natl. Acad. Sci. U. S. A. 118, e2113202118 (2021)] have observed dynamic lipid-lipid correlations in membranes with submicrometer spatial resolution and submillisecond temporal resolution. While short from an instrumentation standpoint, these length and time scales remain long compared to microscopic molecular motions. Theoretical expressions are derived to infer experimentally measurable correlations from the two-body diffusion matrix appropriate for membrane-bound bodies coupled by hydrodynamic interactions. The temporal (and associated spatial) averaging resulting from finite acquisition times has the effect of washing out correlations as compared to naive predictions (i.e., the bare elements of the diffusion matrix), which would be expected to hold for instantaneous measurements. The theoretical predictions are shown to be in excellent agreement with Brownian dynamics simulations of experimental measurements. Numerical results suggest that the experimental measurement of membrane protein diffusion, in complement to lipid diffusion measurements, might help to resolve the experimental ambiguities encountered for certain black lipid membranes.
最近的单分子测量研究[朔赫等人，《美国国家科学院院刊》118，e2113202118（2021年）]已在具有亚微米空间分辨率和亚毫秒时间分辨率的膜中观察到动态脂质-脂质相关性。尽管从仪器角度来看时间较短，但与微观分子运动相比，这些长度和时间尺度仍然较长。通过适合由流体动力学相互作用耦合的膜结合体的两体扩散矩阵，推导出理论表达式以推断实验可测量的相关性。与单纯预测（即扩散矩阵的裸元素）相比，有限采集时间导致的时间（以及相关空间）平均具有消除相关性的效果，而单纯预测预期适用于瞬时测量。理论预测结果与实验测量的布朗动力学模拟结果高度吻合。数值结果表明，膜蛋白扩散的实验测量，作为脂质扩散测量的补充，可能有助于解决某些黑脂质膜所遇到的实验模糊性问题。
