Stark effect spectroscopy of tryptophan

The change in permanent dipole moment (magnitude of delta mu) for the transition from the 1La state to the ground state of tryptophan is the key photophysical parameter for the interpretation of tryptophan fluorescence spectra in terms of static and dynamic dielectric properties of the surrounding m...

Full description

Saved in:
Bibliographic Details
Published in:Biophysical journal 1995-04, Vol.68 (4), p.1583-1591
Main Authors: Pierce, D.W., Boxer, S.G.
Format: Article
Language:English
Subjects:
Biophysical Phenomena
Biophysics
Electrochemistry
Fluorescence Polarization
Melitten - chemistry
Models, Chemical
Photochemistry
Solvents
Spectrometry, Fluorescence
Spectrophotometry - methods
Tryptophan - analogs & derivatives
Tryptophan - chemistry
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The change in permanent dipole moment (magnitude of delta mu) for the transition from the 1La state to the ground state of tryptophan is the key photophysical parameter for the interpretation of tryptophan fluorescence spectra in terms of static and dynamic dielectric properties of the surrounding medium. We report measurement of this parameter by means of electric field effect (Stark) spectroscopy for N-acetyl-L-tryptophanamide (NATA) in two solvents, the single tryptophan containing peptide melittin, and 5-methoxytryptophan. The values ranged from 5.9 to 6.2 +/- 0.4 Debye/f for NATA and melittin, where f represents the local field correction. The 1Lb magnitude of delta mu was much smaller. Application of Stark spectroscopy to these chromophores required decomposition of the near-UV absorption into the 1La and 1Lb bands by measurement of the fluorescence excitation anisotropy spectrum and represents an extension of the method to systems where band overlap would normally preclude quantitative analysis of the Stark spectrum. The results obtained for 5-methoxytryptophan point out limitations of this method of spectral decomposition. The relevance of these results to the interpretation of steady-state and time-resolved spectroscopy of tryptophan is discussed.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(95)80331-0