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Aromatic‐backbone interactions in model α‐helical peptides
Author(s) -
Palermo Nicholas Y.,
Csontos József,
Owen Michael C.,
Murphy Richard F.,
Lovas Sándor
Publication year - 2007
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20578
Subject(s) - chemistry , steric effects , side chain , hydrogen bond , computational chemistry , aromaticity , basis set , molecular dynamics , stereochemistry , crystallography , molecule , density functional theory , organic chemistry , polymer
The effects on helical stability of weak polar interactions between aromatic side‐chains and the peptide backbone were examined. α‐Helical model peptides, hexa‐Ala, with sequential Tyr replacement, were investigated computationally to obtain the geometries and energetics of the interactions. Geometries were obtained with the B3LYP/6‐31G* level of theory. Interaction energies were calculated using BHandHLYP/cc‐pVTZ and an improved method to correct for basis set superposition error when fragmentation caused steric clashes. Both i , i + 1 and i , i − 4 interactions were observed when Tyr was in position i = 5. The position of the aromatic residue in the amino acid sequence was crucial in facilitating aromatic‐backbone interactions. The distance between the center of the aromatic ring of Tyr and the individual interacting backbone atoms ranged from 3.65 to 5.50 Å. The interactions have energies of the same order as hydrogen bonds and, thus, could have a significant impact on the stability of the helix. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007