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Inverse H‐C ex situ HRMAS NMR experiments for solid‐phase peptide synthesis
Author(s) -
Ramadhar Timothy R.,
Amador Fernando,
Ditty Michael J. T.,
Power William P.
Publication year - 2008
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2118
Subject(s) - homonuclear molecule , chemistry , heteronuclear molecule , magic angle spinning , inverse , chemical shift , nuclear magnetic resonance spectroscopy , analytical chemistry (journal) , computational chemistry , stereochemistry , molecule , chromatography , organic chemistry , geometry , mathematics
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 1 H 13 C 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 1 J CH 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 1 H 1 H 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 13 C 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. Copyright © 2008 John Wiley & Sons, Ltd.