Sengupta B, Sengupta P K
Biophysics Division, Saha Institute of Nuclear Physics, 37, Belgachia Road, Calcutta, 700 037, India.
Biochem Biophys Res Commun. 2000 Oct 14;277(1):13-9. doi: 10.1006/bbrc.2000.3622.
A number of recent studies have presented perspectives on the hydrophobic fluorescence probe tryptophan octyl ester (TOE). This molecule has attracted notable attention as a suitable model for the natural fluorophore tryptophan, in case of membrane proteins. We report here, for the first time, the fluorescence emission behaviour of TOE in reverse micelles of aerosol-OT (AOT) in n-heptane, containing different amounts of water. Relevant studies in representative homogeneous solvent media are also included for comparison. The fluorescence emission parameters (especially emission maximum, relative intensity, and anisotropy) of TOE are found to exhibit significant variation upon changes in the water/surfactant molar ratio (w(0)) of the reverse micelles. Fluorescence decay studies on TOE which we have also performed, indicate biexponential decay kinetics in reverse micelles as well as in homogeneous solvent media. The implications of these findings are examined in relation to the potentialities of TOE as a novel fluorescence probe for membrane proteins present in water restricted environments prevailing at the interfaces of biomembranes (for which reverse micelles serve as ideal model systems).
最近的一些研究对疏水荧光探针色氨酸辛酯（TOE）提出了不同观点。在膜蛋白研究中，该分子作为天然荧光团色氨酸的合适模型受到了显著关注。我们首次在此报告了TOE在含有不同水量的正庚烷中气溶胶-OT（AOT）反胶束中的荧光发射行为。为作比较，还纳入了在代表性均相溶剂介质中的相关研究。发现TOE的荧光发射参数（尤其是发射最大值、相对强度和各向异性）会随着反胶束中水/表面活性剂摩尔比（w(0)）的变化而呈现显著变化。我们还对TOE进行了荧光衰减研究，结果表明在反胶束以及均相溶剂介质中，TOE的衰减动力学均为双指数衰减。结合TOE作为新型荧光探针用于生物膜界面处存在的水受限环境中膜蛋白的潜力（反胶束是此类环境的理想模型系统），对这些发现的意义进行了探讨。
