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

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