Blackwell M F, Gounaris K, Zara S J, Barber J
Biophys J. 1987 May;51(5):735-44. doi: 10.1016/S0006-3495(87)83400-8.
The Stern-Volmer theory, in which the quantum yield ratio (Io/I) depends linearly on the quencher concentration, will typically be inapplicable to fluorescence quenching in membranes. Numerical analysis shows that diffusion-controlled quenching results in a nonlinear concentration dependence for diffusion coefficients less than or of the order of 10(-6) cm2 s-1 and probe fluorescence lifetimes in the region of 10-100 ns. Lateral diffusion coefficients in membranes are typically overestimated an order of magnitude or more by the Stern-Volmer theory. An alternative empirical method is presented, which represents nonlinear concentration curves by a single parameter linear approximation determined by a least-squares analysis. The fitting parameter, P, depends on the interaction distance, the membrane thickness, the maximum extent of quenching and, in the case of biexponential probe fluorescence decay, the fluorescence kinetic parameters. P is presented in tabular form for a useful range of these parameters. The method is used to estimate diffusion coefficients for plastoquinone and plastoquinol from pyrene fluorescence quenching in soya bean phosphatidylcholine liposomes. It is found that the diffusion coefficients are nearly equal and in the region of 1.3-3.5 X 10(-7) cm2 s-1 for interaction radii of 1.5-0.5 nm, respectively.
斯特恩 - 沃尔默理论认为量子产率比（Io/I）与猝灭剂浓度呈线性关系，该理论通常不适用于膜中的荧光猝灭。数值分析表明，对于扩散系数小于或约为10^(-6) cm² s⁻¹且探针荧光寿命在10 - 100 ns范围内的情况，扩散控制的猝灭会导致浓度依赖性呈非线性。斯特恩 - 沃尔默理论通常会将膜中的横向扩散系数高估一个数量级或更多。本文提出了一种替代的经验方法，该方法通过最小二乘法分析确定的单参数线性近似来表示非线性浓度曲线。拟合参数P取决于相互作用距离、膜厚度、猝灭的最大程度，对于双指数探针荧光衰减的情况，还取决于荧光动力学参数。文中以表格形式给出了这些参数在有用范围内的P值。该方法用于从大豆磷脂酰胆碱脂质体中芘荧光猝灭来估计质体醌和质体氢醌的扩散系数。结果发现，对于相互作用半径分别为1.5 - 0.5 nm的情况，扩散系数几乎相等，在1.3 - 3.5×10^(-7) cm² s⁻¹范围内。
