Meyer T, Schindler H
Department of Biophysical Chemistry, Biocenter of the University of Basel, Switzerland.
Biophys J. 1988 Dec;54(6):983-93. doi: 10.1016/S0006-3495(88)83036-4.
A method for simultaneous determination of molar weights (M) and lateral diffusion constants (D) of particles in three- and two-dimensional systems is described. Spontaneous concentration fluctuations in space and time are analyzed, by monitoring fluctuations in the fluorescence from fluorescein-labeled molecules (1 dye/molecule is sufficient), excited by a rotating laser spot. For particles in solution, M values are determined over the range of 3 x 10(2) to 3 x 10(11) daltons, and D values can be determined from approximately 10(-7) to 10(-10) cm2/s. The time for a determination is approximately 1 min. Aggregation can be followed by changes of either M or D. This method is used to study the calcium dependence of vesicle aggregation or fusion, and the time course of aggregate formation of porin (an Escherichia Coli outer membrane protein) in lipid monolayers. Essential parameters for the development of the method are described. Equations to estimate the signal-to-noise ratios and to find the optimal free parameters for a specific application are derived. The theoretical predictions for the correlation function of the signal and for the signal-to-noise ratio are compared with observed values.
描述了一种同时测定三维和二维系统中颗粒的摩尔质量（M）和横向扩散常数（D）的方法。通过监测由旋转激光光斑激发的荧光素标记分子（每个分子1个染料就足够）发出的荧光波动，分析空间和时间上的自发浓度波动。对于溶液中的颗粒，M值在3×10²至3×10¹¹道尔顿范围内测定，D值可在约10⁻⁷至10⁻¹⁰cm²/s范围内测定。一次测定的时间约为1分钟。聚集情况可通过M或D的变化来跟踪。该方法用于研究囊泡聚集或融合对钙的依赖性，以及脂质单层中孔蛋白（一种大肠杆菌外膜蛋白）聚集体形成的时间进程。描述了该方法开发的关键参数。推导了估计信噪比以及为特定应用找到最佳自由参数的方程。将信号相关函数和信噪比的理论预测与观测值进行了比较。
