Resolution enhancement by homonuclear J-decoupling: application to three-dimensional solid-state magic angle spinning NMR spectroscopy
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We describe a simple protocol to achieve homonuclear J-decoupling in the indirect dimensions of multidimensional experiments, and to enhance spectral resolution of the backbone Cα carbons in the 3D NCACX experiment. In the proposed protocol, the refocusing of the Cα–CO homonuclear J-couplings is achieved by applying an off-resonance selective π pulse to the CO spectral region in the middle of Cα chemical shift evolution. As is commonly used in solution NMR, a compensatory echo period is used to refocus the unwanted chemical shift evolution of Cα spins, which takes place during the off-resonance selective pulse. The experiments were carried out on the β1 immunoglobulin binding domain of protein G (GB1). In GB1, such implementation results in significantly reduced line widths, and leads to an overall sensitivity enhancement.
KeywordsSolid-state NMR Magic angle spinning Uniformly 13C,15N labeled proteins Assignments Homonuclear decoupling Resolution enhancement
Magic angle spinning
β1 immunoglobulin binding domain of protein G
Time proportional phase increment
Small phase incremental alternation with 64 steps
This research was supported by the University of Guelph (start-up funds to V.L.), the Natural Sciences and Engineering Research Council of Canada (DG250202 to L.S.B. and Grants RG298480-04 to V.L.), the Canada Foundation for Innovation, and the Ontario Innovation Trust. V.L. holds Canada Research Chair in Biophysics, and is a recipient of an Early Researcher Award from the Ontario Ministry of Research and Innovation. L.S. is a recipient of the Ontario Graduate Scholarship. M.A. is a recipient of a Doctoral Studentship from the Ministry of Higher Education and Scientific Research of Egypt.
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