relation: http://d-scholarship-dev.library.pitt.edu/17211/
title: Direct UV Raman monitoring of 3<inf>10</inf>-helix and π-bulge premelting during α-helix unfolding
creator: Mikhonin, AV
creator: Asher, SA
description: We used UV resonance Raman (UVRR) spectroscopy exciting at ∼200 nm within the peptide bond π→π* transitions to selectively study the amide vibrations of peptide bonds during α-helix melting. The dependence of the amide frequencies on their Ψ Ramachandran angles and hydrogen bonding enables us, for the first time, to experimentally determine the temperature dependence of the peptide bond Ψ Ramachandran angle population distribution of a 21-residue mainly alanine peptide. These Ψ distributions allow us to easily discriminate between α-helix, 310-helix and α-helix/bulge conformations, obtain their individual melting curves, and estimate the corresponding Zimm and Bragg parameters. A striking finding is that α-helix melting is more cooperative and shows a higher melting temperature than previously erroneously observed. These Ψ distributions also enable the experimental determination of the Gibbs free energy landscape along the Ψ reaction coordinate, which further allows us to estimate the free energy barriers along the AP melting pathway. These results will serve as a benchmark for the numerous untested theoretical studies of protein and peptide folding. © 2006 American Chemical Society.
date: 2006-10-25
type: Article
type: PeerReviewed
format: text/plain
language: en
rights: attached
identifier: http://d-scholarship-dev.library.pitt.edu/17211/1/licence.txt
identifier:   Mikhonin, AV and Asher, SA  (2006) Direct UV Raman monitoring of 3<inf>10</inf>-helix and π-bulge premelting during α-helix unfolding.  Journal of the American Chemical Society, 128 (42).  13789 - 13795.  ISSN 0002-7863     
relation: 10.1021/ja062269+