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

Abstract

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 15N and 13C. 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 15N-13C magnetization transfer (simultaneous 15N→13C′ and 15N→13Cα), Bro-DBP has almost the same 15N→13Cα efficiency while offers 30–40% enhancement on 15N→13C′ transfer, compared to TEDOR. Besides, Bro-DBP can also be used as a carbonyl (13C′)-selected method, whose 15N→13C′ 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-13C,15N]-Met-Leu-Phe-OH (fMLF) peptide and the U-13C, 15N labeled β1 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.