Peptide bond distortions from planarity: new insights from quantum mechanical calculations and peptide/protein crystal structures.

ABSTRACT: By combining quantum-mechanical analysis and statistical survey of peptide/protein structure databases we here report a thorough investigation of the conformational dependence of the geometry of peptide bond, the basic element of protein structures. Different peptide model systems have been studied by an integrated quantum mechanical approach, employing DFT, MP2 and CCSD(T) calculations, both in aqueous solution and in the gas phase. Also in absence of inter-residue interactions, small distortions from the planarity are more a rule than an exception, and they are mainly determined by the backbone ψ dihedral angle. These indications are fully corroborated by a statistical survey of accurate protein/peptide structures. Orbital analysis shows that orbital interactions between the σ system of

SUBMITTER: Improta R 

PROVIDER: S-EPMC3174960 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature