Issue 39, 2011

J-coupling constants for a trialanine peptide as a function of dihedral angles calculated by density functional theory over the full Ramachandran space

Abstract

We present 13 3J, seven 2J and four 1J coupling constants (24 in all) calculated using B3LYP/D95** as a function of the ϕ and ψ Ramachandran dihedral angles of the acetyl(Ala)3NH2 capped trialanine peptide over the entire Ramachandran space. With the exception of three of these J couplings, all show significant dependence upon both dihedral angles. For each J coupling considered, a two dimensional grid with respect to ϕ and ψ angles can be used to interpolate the values for any pair of ϕ and ψ values. Such simple interpolation is shown to be very accurate. Most of these calculated J couplings should prove useful for improving the accuracy of the determination of peptide and protein structures from NMR measurements in solution over that provided by the common procedure of treating the J couplings as functions of a single dihedral angle by means of Karplus-type fittings.

Graphical abstract: J-coupling constants for a trialanine peptide as a function of dihedral angles calculated by density functional theory over the full Ramachandran space

Supplementary files

Article information

Article type
Paper
Submitted
26 Feb 2011
Accepted
22 Jul 2011
First published
06 Sep 2011

Phys. Chem. Chem. Phys., 2011,13, 17484-17493

J-coupling constants for a trialanine peptide as a function of dihedral angles calculated by density functional theory over the full Ramachandran space

P. Salvador, I. (. Tsai and J. J. Dannenberg, Phys. Chem. Chem. Phys., 2011, 13, 17484 DOI: 10.1039/C1CP20520J

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