Conformation-dependent: ^lh (proton) NMR chemical shifts of chemotactic peptide, (N-For-Tyr-Gly-Leu-OMe) N

The chemotactic peptide N-For-Tyr-Gly-Leu-OMe yielded extremely well resolved H-1 NMR spectra in CDCl₃ and DMSO-d₆. This spectrum in CDCI₃ shows a broad signal and disappears due to the addition of D₂O. Thus, H-1 NMR spectra of NH groups in amino acids are distinguishable in DMSO-d₆. The solvent dependence studies of the present investigated peptide shows that all ligands, Gly NH, Leu NH, and Tyr NH are well resolved and their chemical shifts are significantly identified. These studies show that ligand NH protons are in slow exchange situation and signals for NH protons will appear as a doublet and this disappears at 100% concentration. The proton resonance for formyl hydrogen is also observed and it is independent with solvent. H-1 NMR results in the temperature range of 283 K to 333 K were obtained to understand the influence of the temperature on the chemical shift values of NH protons. This observation implies that the Gly NH and Leu NH protons are involved in an intra molecular hydrogen bond. In this study, it is observed that the formyl H chemical shift fairly changes with the temperature.