Line narrowing in spectra of proteins dissolved in a dilute liquid crystalline phase by band-selective adiabatic decoupling: Application to 1HN-15N residual dipolar coupling measurements

Abstract

Residual heteronuclear dipolar couplings obtained from partially oriented protein samples can provide unique NMR constraints for protein structure determination. However, partial orientation of protein samples also causes severe 1 H line broadening resulting from residual 1 H- 1 H dipolar couplings. In this communication we show that band-selective 1 H homonuclear decoupling during data acquisition is an efficient way to suppress residual 1 H- 1 H dipolar couplings, resulting in spectra that are still amenable to solution NMR analysis, even with high degrees of alignment. As an example, we present a novel experiment with improved sensitivity for the measurement of one-bond 1 H N - 15 N residual dipolar couplings in a protein sample dissolved in magnetically aligned liquid crystalline bicelles.