Hydrogen bonding effects on 31P NMR shielding in the pyrophosphate group of NADPH bound to L. casei dihydrofolate reductase

AbstractA comparison of 31P NMR chemical shift data and X-ray structural data [Filman, D.J., Bolin, J.T., Matthews, D.A. and Kraut, J. (1982) J. Biol. Chem. 257, 13663–13672] for complexes of NADPH with L. casei dihydrofolate reductase indicates that solvation effects play a major role in influencing the 31P shielding of the pyrophosphate nuclei whereas changes in P-O-C5-H5' torsion angle have little effect

Does a 2 ← 5β-turn structure exist in enkephalins? Study of a fully protected Leu-enkephalin in organic solution by 17O-NMR

AbstractThe 17O chemical shifts of the Gly-2 and Gly-3 oxygens of a fully protected Leu-enkephalin were measured to be identical in acetone solution. This allows the conclusion that neither of these peptide oxygens is hydrogen bonded and that no specific 2 ← 5 β-turn structure exists to an appreciable extent