Band-Selective¹H−¹³C Cross-Polarization in Fast Magic Angle Spinning Solid-State NMR Spectroscopy

Abstract

A magic angle spinning (MAS) NMR technique to transfer polarization from protons to a specific set of the (13)C spins is introduced for the study of biomolecular samples in the solid-state. Ultrafast (>60 kHz) MAS and low irradiation rf fields are used to achieve band-selective Hartmann-Hahn cross-polarization (CP) between the whole proton bath and carbons whose resonances are close to the (13)C-transmitter offset. When compared to conventional, broadband (1)H-(13)C CP, the band-selective experiment can be established without any loss of sensitivity when polarizing the aliphatic signals of a protein sample, and with a significant gain when polarizing carbonyls. This scheme can be used as a building block in 2D (13)C-(13)C homonuclear correlation experiments to obtain a faster and more sensitive characterization of biological solids.

Spinning proteins, the faster, the better?

“…In this context, it is useful and possible to develop low-power pulse schemes for all time periods of the experiment including cross-polarization [20][21][22] and homonuclear polarization transfer, e.g., DREAM and finite-pulse RFDR to name two arbitrary chosen possibilities [23][24][25][26].…”

Development of a rapid method for the quantification of cellulose in tobacco by 13 C CP/MAS NMR

“…Acquiring high resolution NMR in solid systems was difficult because of the line broadening by chemical shift anisotropy and direct dipolar interaction of polar molecules (Maciel, 1984). This problem was addressed by the development of magic-anglespinning (MAS) (Hartmann & Hahn, 1962;Wickramasinghe & Ishii, 2006) and cross-polarization (CP) (Hartmann & Hahn, 1962;Laage et al, 2008), where spectral lines were narrowed and signal was enhanced, as well as their combination (CP/MAS) (Schaefer & Stejskal, 1976;Song, Ge, Xu, Chen, & Zhang, 2014).…”

BSH-CP based 3D solid-state NMR experiments for protein resonance assignment

“…Under these conditions (high field of 700-900 MHz, moderate MAS rate *20 kHz), PDSD, DARR and MIRROR become less efficient due to an increased Zeeman energy difference and better averaging of dipolar couplings. The DREAM scheme works well when the spinning rate considerably exceeds the isotropic chemical shift difference of CO and CA spins (Laage et al 2008;Vijayan et al 2009), and thus it is more suitable for small rotor sizes with small active sample volume, which may not be favorable if enough sample is available to fill larger rotors (e.g. 3.2 mm outer diameter) (Demers et al 2011).…”