¹ H- ¹ H 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 strong ¹ H- ¹ H couplings that broaden ¹ H magic angle spinning (MAS) spectra of solids. The approach facilitates ¹⁵ N- ¹ H correlation experiments as well as experiments for the measurement of ¹ H- ¹ H distances. The distance measurement relies on the excellent resolution in the ¹ H MAS spectrum and homonuclear double quantum recoupling techniques. The ¹ H- ¹ H dipolar recoupling 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 [ ² H, ¹⁵ N] labeled materials and back-exchanged in H ₂ O.