A METHOD FOR ESTIMATING LATERAL DIFFUSION-COEFFICIENTS IN MEMBRANES FROM STEADY-STATE FLUORESCENCE QUENCHING STUDIES
A METHOD FOR ESTIMATING LATERAL DIFFUSION-COEFFICIENTS IN MEMBRANES FROM STEADY-STATE FLUORESCENCE QUENCHING STUDIES
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DOI：
10.1016/s0006-3495(87)83400-8
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发表时间：
1987-05-01
影响因子：
3.4
通讯作者：
BARBER, J
中科院分区：
文献类型：
--
作者：
BLACKWELL, MF;GOUNARIS, K;BARBER, J
Stern-Volmer理论，其中量子产率比（I 0/I）线性依赖于猝灭剂浓度，通常不适用于膜中的荧光猝灭。数值分析表明，扩散控制淬火的结果在一个非线性的浓度依赖性的扩散系数小于或为10-6 cm 2 s-1和探针的荧光寿命在10-100 ns的区域。膜中的横向扩散系数通常被Stern-Volmer理论高估一个数量级或更多。提出了一种替代的经验方法，它表示由最小二乘分析确定的单参数线性近似的非线性浓度曲线。拟合参数P取决于相互作用距离、膜厚度、淬灭的最大程度，并且在双指数探针荧光衰减的情况下，取决于荧光动力学参数。P以表格形式给出了这些参数的有用范围。利用芘荧光猝灭法测定了质体醌和质体醌醇在大豆磷脂酰胆碱脂质体中的扩散系数。发现扩散系数几乎相等，在1.3-3.5 × 10 - 4的范围内。10-7 cm ~ 2s ~（-1）。
The Stern-Volmer theory, in which the quantum yield ratio (I0/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 cm2s-1 and probe fluorescence lifetimes in the region of 10-100 ns. Lateral diffusion coefficients in membranes are typically overestimated an order to 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 .times. 10-7 cm2 s-1 for interaction radii of 1.5-0.5 nm, respectively.