Eur. Phys. J. D 20, 583-587 (2002)
https://doi.org/10.1140/epjd/e2002-00149-4

Electric dipole moments and conformations of isolated peptides

¹ Laboratoire de Spectrométrie Ionique et Moléculaire (UMR 5579 du CNRS) , Université Lyon I et CNRS, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France
² Department of Chemistry, Northwestern University 2145 Sheridan Road, Evanston, Illinois, 60208, USA

Corresponding author: ^a antoine@lasim.univ-lyon1.fr

Received: 4 January 2002
Published online: 13 September 2002

Abstract

The electric dipole moments of the isolated amino acid tryptophan and small glycine-based peptides (WG_n, , W = tryptophan, G = glycine) have been measured by deflection of a molecular beam in an inhomogeneous electric field. The measurements are compared to the results of ab initio calculations and Monte-Carlo simulations. The conformation and the flexibility of the peptides, at different temperatures, are discussed. The WG_n peptides are much more floppy than an isolated tryptophan, even a single glycine is enough to make the peptide floppy on the timescale of the electric deflection measurements.