Band-Selective 1H−13C Cross-Polarization in Fast Magic Angle Spinning Solid-State NMR Spectroscopy
Ségolène Laage†, Alessandro Marchetti†, Julien Sein†, Roberta Pierattelli‡, Hans Juergen Sass§, Stephan Grzesiek§, Anne Lesage†, Guido Pintacuda*† and Lyndon Emsley*†
A magic angle spinning (MAS) NMR technique to transfer polarization from protons to a specific set of the 13C 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 13C-transmitter offset. When compared to conventional, broadband 1H−13C 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 13C−13C homonuclear correlation experiments to obtain a faster and more sensitive characterization of biological solids.