Timothy Ramadhar - Inverse H-C ex situ HRMAS NMR experiments for solid-phase peptide synthesis

Version 1

      Publication Details (including relevant citation   information):

      Timothy R. Ramadhar; Fernando Amador, Michael J. T. Ditty,   William P. Power. Magnetic Resonance in Chemistry,   2008, 46, 30-35.

      Abstract:

      The growing importance of solid-phase peptide synthesis (SPPS)   has necessitated the development of spectroscopic experiments   that can be used to obtain structural and conformational   information on resin-bound peptides. Despite the utility of   two-dimensional high-resolution magic angle spinning (HRMAS) NMR   experiments that provide homonuclear shift correlations,   experiments that provide heteronuclear shift correlations are   necessary for complex conformational and structural elucidatory   problems. Here we report the optimization and implementation of   non-gradient inverse NMR experiments for acquiring the   1H[BOND]13C   shift correlations of resin-bound peptides. The use of   non-gradient experiments is advantageous as many magic angle   spinning (MAS) probes do not possess gradient coils. An HRMAS   BIRD-HMQC experiment with a reduced   1JCH constant has proven very   suitable for obtaining one-bond correlations. Long-range   correlations can be interpolated by using a non-gradient HRMAS   CT-HMBC-1 experiment where the resulting data is processed with   forward linear prediction. It has been shown that removing the   effects of 1H[BOND]1H   J-modulation is crucial in order to view cross peaks   that correspond to long-range correlations. Additionally, both   experiments prove extremely useful over routine one-dimensional   13C HRMAS experiments for extracting carbon chemical   shift data. The non-gradient HRMAS BIRD-HMQC and CT-HMBC-1   experiments can be used to assist in conformational analysis and   to identify and deconvolute situations where accidental   equivalence and seemingly correlated isochronous signals arise.

      Address (URL): http://dx.doi.org/10.1002/mrc.2118