A spectroscopic and biochemical study of the non-invasive optical probe 7-azatryptophan and its chromophoric portion 7-azaindole

Abstract

The aim of this work is to demonstrate the feasibility and ease with which the non-natural amino acid 7-azatryptophan can be used as a noninvasive optical probe of protein structure and dynamics. 7-Azatryptophan is a tryptophan analog possessing many properties which make it an ideal optical probe and a possible alternative to tryptophan. These include its well-behaved spectroscopic properties, its ability to be incorporated into bacterial protein and synthetic peptides, and the capability of a synthetic peptide containing 7-azatryptophan to complex with an enzyme. Unlike tryptophan, 7-azatryptophan has a single exponential fluorescence decay in aqueous solution. Its absorption and fluorescence spectra are distinguishable from those of tryptophan and its fluorescence spectrum is sensitive to the environment.