H-1-H-1 MAS correlation spectroscopy and distance measurements in a deuterated peptide

In this Communication, we demonstrate the use of deuteration together with back substitution of exchangeable protons as a means of attenuating the str ong H-1-H-1 couplings that broaden H-1 magic angle spinning (MAS) spectra o f solids. The approach facilitates N-15-H-1 correlation experiments as well as experiments for the measurement of H-1-H-1 distances. The distance meas urement relies on the excellent resolution in the H-1 MAS spectrum and homo nuclear double quantum recoupling techniques. The H-1-H-1 dipolar recouplin g can be analyzed in an analytical fashion by fitting the data to a 2- or 3 -spin system. The experiments are performed on a sample of the dipeptide N- Ac-Val-Leu-OH, which was synthesized from uniformly [H-2, N-15] labeled mat erials and back-exchanged in H2O. (C) 2001 Academic Press.