Broadband heteronuclear dipolar recoupling without 1H decoupling in solid-state NMR using simple cross-polarization methods

Heteronuclear dipolar recoupling experiments without 1H decoupling based on simple cross polarization are introduced for applications in biological solid-state NMR. It is shown that standard or adiabatic variants of the cross-polarization experiment with irradiation on the low-γ (e.g., 13C,15N) spins even at modest spinning frequencies enable efficient band-selective or broadband dipolar recoupling without the need for intense 1H decoupling. This facilitates experiments on expensive isotope-labelled protein samples for which sample heating by intense 1H decoupling may lead to sample detoriation. The principle is demonstrated numerically and experimentally on uniformly 13C,15N-labelled samples of GB1 and fibrils of hIAPP (20–29) from the human islet amyloid labelled on the FGAIL part.