Predicting cyclic peptide chemical shifts using quantum mechanical calculations

A hybrid sequential molecular mechanics and quantum mechanical approach to modeling cyclic peptides has led to an effective method for predicting their 1H and 13C NMR chemical shift values. The method was first developed to predict chemical shifts in chloroform before being adapted to a more peptide friendly solvent, DMSO. Finally the effectiveness of this method was tested in a blind fashion and excellent agreement with the experimental NMR chemical shifts was observed.