Toward direct determination of conformations of protein building units from multidimensional NMR experiments. V. NMR chemical shielding analysis of N‐formyl‐serinamide, a model for polar side‐chain containing peptides

Knowledge of chemical shift-structure relationships could greatly facilitate the NMR chemical shift assignment and structure refinement processes that occur during peptide/protein structure determination via NMR spectroscopy. To determine whether such correlations exist for polar side chain containing amino acid residues the serine dipeptide model, For-L-Ser-NH2, was studied. Using the GIAO-RHF/6-31G(d) and GIAO-RHF/TZ2P levels of theory the NMR chemical shifts of all hydrogen ( 1 H N , 1 H, 1 H 1 , 1 H 2 ), carbon ( 13 C, 13 C, 13 C) and nitrogen ( 15 N) atoms have been computed for all 44 stable conformers of For-L-Ser-NH2. An attempt was made to establish correlation between chemical shift of each nucleus and the major conformational variables ( 0, , , 1, , 1 and 2 ). At both levels of theory a linear correlation can be observed between 1 H/, 13 C/, and 13 C/. These results indicate that the