Conformations of Gly(n)H+ and Ala(n)H+ peptides in the gas phase

Robert R. Hudgins, Yi Mao, Mark A Ratner, Martin F. Jarrold

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Abstract

High-resolution ion mobility measurements and molecular dynamics simulations have been used to probe the conformations of protonated polyglycine and polyalanine (Gly(n)H+ and Ala(n)H+, n = 3-20) in the gas phase. The measured collision integrals for both the polyglycine and the polyalanine peptides are consistent with a self-solvated globule conformation, where the peptide chain wraps around and solvates the charge located on the terminal amine. The conformations of the small peptides are governed entirely by self-solvation, whereas the larger ones have additional backbone hydrogen bonds. Helical conformations, which are stable for neutral Ala(n) peptides, were not observed in the experiments. Molecular dynamics simulations for Ala(n)H+ peptides suggest that the charge destabilizes the helix, although several of the low energy conformations found in the simulations for the larger Ala(n)H+ peptides have small helical regions.

Original languageEnglish
Pages (from-to)1591-1597
Number of pages7
JournalBiophysical Journal
Volume76
Issue number3
Publication statusPublished - 1999

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ASJC Scopus subject areas

  • Biophysics

Cite this

Hudgins, R. R., Mao, Y., Ratner, M. A., & Jarrold, M. F. (1999). Conformations of Gly(n)H+ and Ala(n)H+ peptides in the gas phase. Biophysical Journal, 76(3), 1591-1597.