Institute of General Food Chemistry, Faculty of Biotechnology and Food Sciences, Technical University of Lodz, ul. Stefanowskiego 4/10, 90-924 Lodz, Poland.
Spectrochim Acta A Mol Biomol Spectrosc. 2012 Dec;98:282-9. doi: 10.1016/j.saa.2012.08.017. Epub 2012 Aug 19.
Previously reported flash photolysis studies showed that the triplet state lifetime of aqueous indoles is μs long (12.5 μs for tryptophan [10]), while other recently reported phosphorescence lifetimes of aqueous indoles, determined from photon counting phosphorescence techniques, vary from μs (approximately 40 μs [11]) to ms (5 ms for indole [12]). This study was motivated to explain the discrepancy regarding the intrinsic triplet state lifetime of aqueous indole and its derivatives: tryptophan and N-acetyl-L-tryptophanamide (NATA). For this purpose, a new methodology based on both fluorescence and phosphorescence decay kinetics incorporating the heavy atom effect have been applied in order to determine some quantitative parameters of the photophysics of indole and its derivatives. Additionally, we have also determined the triplet state lifetimes of the studied indoles using flash photolysis in which contributions from both a first order component and a second order component (from triplet-triplet annihilation) have been taken into account in the triplet state depopulation. The measured phosphorescence lifetime of the indoles examined measures between the values reported by Fischer and Strambini and is consistent with the triplet state lifetime determined from flash photolysis. We hope that the results obtained in this paper would be helpful for deriving structural and dynamical information from phosphorescence data of tryptophan residues in proteins.
先前报道的闪光光解研究表明，水合吲哚的三重态寿命为 μs 级（色氨酸为 12.5 μs[10]），而最近报道的其他水合吲哚的磷光寿命，通过光子计数磷光技术确定，从 μs（约 40 μs[11]）到 ms（吲哚为 5 ms[12]）不等。本研究旨在解释关于水合吲哚及其衍生物（色氨酸和 N-乙酰-L-色氨酸酰胺（NATA））固有三重态寿命的差异。为此，应用了一种新的基于荧光和磷光衰减动力学的方法，结合重原子效应，以确定吲哚及其衍生物光物理的一些定量参数。此外，我们还使用闪光光解法测定了所研究吲哚的三重态寿命，其中考虑了三重态-三重态湮灭的一级和二级分量对三重态去激发的贡献。所测定的吲哚磷光寿命介于 Fischer 和 Strambini 报道的值之间，与闪光光解法确定的三重态寿命一致。我们希望本文的研究结果有助于从蛋白质中色氨酸残基的磷光数据中推导出结构和动力学信息。
