AMINO/AROMATIC INTERACTIONS IN PROTEINS - IS THE EVIDENCE STACKED AGAINST HYDROGEN-BONDING

摘要: Abstract We investigate the suggestion that aromatic rings can act as hydrogen-bond acceptors in proteins, by an analysis of 55 non-homologous high-resolution protein chain structures. Approximately 10% interactions between sp2 hybridized nitrogen atoms, from either side-chains or main-chains, and phenylalanine tyrosine have atom positioned above ring. In these instances, however, atoms tend to form stacked with rings, geometries outnumbering amino/aromatic hydrogen bonds around 2·5:1. The statistically expected distribution, contrast, would only a few structures many more larger interplanar angles, corresponding bonds. Thus, although we do find some unconventional bonds, they are clearly disfavoured relative geometries. geometries, nitrogen-bearing groups observed fulfil their hydrogen-bonding potential forming conventional, energetically stronger, other solvent. This may explain favourability stacking. ab initio calculations gas phase interaction energies for three model systems generally favour hydrogen-bonded over differences small enough be outweighed easily additional conventional bonding