Electron density in the peptide bonds of crambin

The electron density in the peptide bonds of crambin, a plant-seed hydropho bic globular protein with 46 residues and 642 atoms, is studied both theore tically and experimentally. The results of density functional calculations of crambin in vacuo for the deformation electron density in its peptide bon ds are compared with the electronic distribution obtained from ultra-high-r esolution X-ray crystallography, The comparison is centered on the average peptide-bond map, where the experimental results are dearest. Theory is the n used to ascertain on differences among peptide bonds in different chemica l environments. (C) 2000 Elsevier Science Ltd. All rights reserved.