Sensitivity-enhanced 2D IPAP, TROSY-anti-TROSY, and E.COSY experiments: alternatives for measuring dipolar 15N-1HN couplings.

Sensitivity-enhanced versions of the IPAP, TROSY-anti-TROSY, and E.COSY experiments for measuring one-bond 15N-1HN couplings are presented. Together with the previously developed sensitivity-enhanced E.COSY-type HSQC experiment they comprise a suite of sensitivity-enhanced experiments that allows one to chose the optimal spectrum for accurate measurement of one-bond 15N-1HN residual dipolar couplings in proteins. Since one-bond 15N-1HN residual dipolar couplings play uniquely important roles in structural NMR, these additional methods provide further tools for improving structure determination of proteins and other biological macromolecules.