Dependence of tryptophan emission wavelength on conformation in cyclic hexapeptides
Chia-Pin Pan1, Patrik R Callis, Mary D Barkley
1Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.
Abstract:
The wavelength of maximum emission of tryptophan depends on the local electrostatic environment of the indole chromophore. The time-resolved emission spectra of seven rigid cyclic hexapeptides containing a single tryptophan residue were measured. The emission maxima of the three decay-associated spectra for the seven peptides ranged from 341 to 359 nm, suggesting that different tryptophan rotamers have different emission maxima even in the case of solvent-exposed tryptophans. This conclusion is supported by quantum mechanical/molecular dynamics simulations of the six canonical side chain rotamers of tryptophan in solvated hexapeptides. The calculated range of emission maxima for the tryptophan rotamers of the seven peptides is 344-365 nm. The precision of the wavelength calculations and the peptide, water, and charged side chain contributions to the spectral shifts are examined. The results indicate that the emission maxima of decay-associated spectra can aid in the assignment of fluorescence lifetimes to tryptophan rotamers.
More Related Videos
12:07Chemical Modification of the Tryptophan Residue in a Recombinant Ca2+-ATPase N-domain for Studying Tryptophan-ANS FRET
Published on: October 9, 2021
10:31Residue-Specific Exchange of Proline by Proline Analogs in Fluorescent Proteins: How "Molecular Surgery" of the Backbone Affects Folding and Stability
Published on: February 3, 2022
Related Concept Videos
Transcription Attenuation in Prokaryotes
There are several different mechanisms used to attenuate transcription. In ribosome mediated...
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group with both...
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
Variables Affecting Phosphorescence and Fluorescence
Repressible Operon: trp Operon
