A robust heteronuclear dipolar recoupling method comparable to TEDOR for proteins in magic-angle spinning solid-state NMR

In this letter, we propose a robust heteronuclear dipolar recoupling method for proteins in magic-angle spinning (MAS) solid-state NMR. This method is as simple, robust and efficient as the well-known TEDOR in the aspect of magnetization transfer between N-15 and C-13. Deriving from our recent band-selective dual back-to-back pulses (DBP) (Zhang et al., 2016), this method uses new phase-cycling schemes to realize broadband DBP (Bro-DBP). For broadband N-15-C-13 magnetization transfer (simultaneous N-15 -> C-13' and N-15 -> C-13 alpha), Bro-DBP has almost the same N-15 -> C-13 alpha efficiency while offers 30-40% enhancement on N-15 -> C-13' transfer, compared to TEDOR. Besides, Bro-DBP can also be used as a carbonyl (C-13') selected method, whose N-15 -> C-13' efficiency is up to 1.7 times that of TEDOR and is also higher than that of band-selective DBP. The performance of Bro-DBP is demonstrated on the N-formyl-[U-C-13, N-15]-Met-Leu-Phe-OH (fMLF) peptide and the U-C-13, N-15 labeled beta 1 immunoglobulin binding domain of protein G (GB1) microcrystalline protein. Since Bro-DBP is as robust, simple and efficient as TEDOR, we believe it is very useful for protein studies in MAS solid-state NMR. (C) 2017 Elsevier Inc. All rights reserved.