Origin of Tryptophan Fluorescence Lifetimes Part 1. Fluorescence Lifetimes Origin of Tryptophan Free in Solution

Fluorescence intensity decays of L-tryptophan free in polar, hydrophobic and mixture of polar-hydrophobic solvents were recorded along the emission spectrum (310–410 nm). Analysis of the data show that emission of tryptophan occurs with two lifetimes in 100 % polar and hydrophobic environments. The...

Full description

Saved in:
Bibliographic Details
Published in:Journal of fluorescence 2014, Vol.24 (1), p.93-104
Main Author: Albani, J. R.
Format: Article
Language:English
Subjects:
Analytical Chemistry
Biochemistry
Biological and Medical Physics
Biomedical and Life Sciences
Biomedicine
Biophysics
Biotechnology
Electronics
Emission
Ethanol
Ethyl alcohol
Excitation
Fluorescence
Hydrophobic and Hydrophilic Interactions
Original Paper
Origins
Solutions
Time Factors
Tryptophan
Tryptophan - chemistry
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Fluorescence intensity decays of L-tryptophan free in polar, hydrophobic and mixture of polar-hydrophobic solvents were recorded along the emission spectrum (310–410 nm). Analysis of the data show that emission of tryptophan occurs with two lifetimes in 100 % polar and hydrophobic environments. The values of the two lifetimes are not the same in both environments while their populations (pre-exponentials values) are identical. Fluorescence lifetimes and pre-exponentials values do not change with the excitation wavelength and thus are independent of excitation energy. Our results indicate that tryptophan emission occurs from two specific sub-structures existing in the excited state. These sub-structures differ from those present in the ground states and characterize an internal property and/or organization of the tryptophan structure in the excited state. By sub-substructure, we mean here tryptophan backbone and its electronic cloud. In ethanol, three fluorescence lifetimes were measured; two lifetimes are very close to those observed in water (0.4–0.5 ns and 2–4 ns). Presence of a third lifetime for tryptophan in ethanol results from the interaction of both hydrophobic and hydrophilic dipoles or chemical functions of ethanol with the fluorophore.
ISSN:1053-0509
1573-4994
DOI:10.1007/s10895-013-1277-8