Conformations and properties of the L ‐tryptophyl‐containing peptides in solution, depending on the pH—Theoretical study vs. experiments

The conformational preference and electronic properties of three L ‐tryptophyl‐containing dipeptides, i.e., glycyl‐ L ‐tryptophane (H‐Gly‐Trp‐OH), L ‐alanyl‐ L ‐tryptophane (H‐Ala‐Trp‐OH), and L ‐methionyl‐ L ‐tryptophane ( L ‐Met‐Trp‐OH) in solution depending on the pH of the media are studied both theoretically and experimentally. The effect of the protonation of the COO − and deprotonation of the NH   3 +as well as the alkaline hydrolysis of the amide fragment in a strong basic media on the electronic spectra are discussed. Ab initio and density functional theory (DFT) methods as well as the time‐dependent DFT (TD‐DFT) method as a function of the basis set are performed with a view to obtain the geometry and electronic properties of all of the species as well as the intermediate, obtained in the alkaline hydrolysis mechanism. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 727–734, 2010. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com