MECHANISM OF MEMBRANE-POTENTIAL SENSITIVITY OF FLUORESCENT MEMBRANE PROBE MEROCYANINE-540
MECHANISM OF MEMBRANE-POTENTIAL SENSITIVITY OF FLUORESCENT MEMBRANE PROBE MEROCYANINE-540
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DOI：
10.1021/bi00617a024
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发表时间：
1978-01-01
期刊：
影响因子：
2.9
通讯作者：
WEBB, WW
中科院分区：
文献类型：
--
作者：
DRAGSTEN, PR;WEBB, WW
膜染色染料mercury 540（M-540）的荧光和光吸收已被广泛用于测量细胞跨膜电位。通过测量M-540的荧光偏振及其对半球形脂质双层膜中膜电位变化的响应，研究了这些光学变化的分子机制。荧光在2个不同的时间尺度上响应于电位阶跃：上升时间小于6 μ s的仪器能力的快速响应和时间常数约为10-1 s的缓慢响应。两种响应幅度都与膜电位变化的幅度成比例，并且都需要M-540在膜上的不对称分布。缓慢的响应归因于膜中染料浓度的净变化。的快速响应似乎是占主导地位的染料分子在膜中的取向的分布的变化，伴随着扰动的单体-二聚体平衡，由于施加的电场与M-540的永久分子偶极矩的相互作用。快速荧光响应的幅度是浓度依赖性的，并且可以通过包括膜饱和效应和在高染料浓度下膜中存在非荧光二聚体物质来建模。其他研究者报告的吸光度变化与该模型机制一致。
The fluorescence and optical absorption of the membrane-staining dye merocyanine 540 (M-540) have been widely used to measure cellular transmembrane potentials. The molecular mechanisms of these optical changes were studied by measuring the fluorescence polarization of M-540 and its response to membrane potential changes in hemispherical lipid bilayer membranes. The fluorescence responds to a potential step in 2 distinct time scales: a fast response with a rise time less than the instrumental capability of 6 .mu.s and a slow response with a time constant around 10-1 s. Both response amplitudes are proportional to the amplitude of the membrane potential change and both require an asymmetrical distribution of M-540 across the membrane. The slow response is ascribed to a net change of the dye concentration in the membrane. The fast response appears to be dominated by a change in the distribution of orientations of the dye molecules in the membrane, with a concomitant perturbation of a monomer-dimer equilibrium, due to interaction of the applied electric field with the permanent molecular dipole moment of M-540. The amplitude of the fast fluorescence response is concentration dependent and can be modeled by including membrane saturation effects and the presence of a nonfluorescent dimer species in the membrane at high dye concentrations. Absorbance changes reported by other investigators are consistent with this model mechanism.