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Title

Intramolecular interactions of L-phenylalanine revealed by inner shell chemical shift

Author(s)

Ganesan, Aravindhan;  Wang, Feng

Abstract

Intramolecular interactions of the functional groups, carboxylic acid, amino, and phenyl in L-phenylalanine have been revealed through inner shell chemical shift. The chemical shift and electronic structures are studied using its derivatives, 2-phenethylamine (PEA) and 3-phenylpropionic acid (PPA), through substitutions of the functional groups on the chiral carbon C-alpha, i.e., carboxylic acid (-COOH) and amino (-NH2) groups. Inner shell ionization spectra of L-phenylalanine are simulated using density functional theory based B3LYP/TZVP and LB94/et-pVQZ models, which achieve excellent agreement with the most recently available synchrotron sourced x-ray photoemission spectroscopy of L-phenylalanine (Elettra, Italy). The present study reveals insight into behavior of the peptide bond (CO-NH) through chemical shift of the C-1-C-alpha-C-beta(-C-gamma) chain and intramolecular interactions with phenyl. It is found that the chemical shift of the carbonyl C-1(=O) site exhibits an apparently redshift (smaller energy) when interacting with the phenyl aromatic group. Removal of the amino group (-NH2) from L-phenylalanine (which forms PPA) brings this energy on C-1 close to that in L-alanine (delta<0.01 eV). Chemical environment of C-alpha and C-beta exhibits more significant differences in L-alanine than in the aromatic species, indicating that the phenyl group indeed affects the peptide bond in the amino acid fragment. No direct evidences are found that the carbonyl acid and amino group interact with the phenyl ring through conventional hydrogen bonds.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Molecular Simulation

Source

Journal of Chemical Physics: BioChemical Physics, Vol. 3, no. 7 (Jul 2009), article no. 044321

Publication year

2009

FOR Code(s)

0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics;  0306 Physical Chemistry (Incl. Structural)

Keyword(s)

3-phenylpropionic acid;  Amino acids;  Binding energies;  Gas phase;  L-phenylalanine;  Spectroscopy

Publisher

American Institute of Physics

ISSN

1931-9223

Publisher URL

http://dx.doi.org/10.1063/1.3187033

Copyright

Copyright © 2009 American Institute of Physics. Author version of the paper reproduced here in accordance with the copyright policy of the publisher.

Additional information

This article was originally published in the Journal of Chemical Physics and was also selected to appear in the July 2009 issue of JCP: BioChemical Physics, which features biophysical content from the Journal of Chemical Physics compiled into monthly issues. For the original article, see: http://hdl.handle.net/1959.3/62788.

Full text

Peer reviewed