Simultaneous acquisition of 13Cα-15N and 1H-15N-15N sequential correlations in proteins: application of dual receivers in 3D HNN.

We describe here, adaptation of the HNN pulse sequence for multiple nuclei detection using two independent receivers by utilizing the detectable (13)C(α) transverse magnetization which was otherwise dephased out in the conventional HNN experiment. It enables acquisition of 2D (13)C(α)-(15)N sequential correlations along with the standard 3D (15)N-(15)N-(1)H correlations, which provides directionality to sequential walk in HNN, on one hand, and enhances the speed of backbone assignment, on the other. We foresee that the implementation of dual direct detection opens up new avenues for a wide variety of modifications that would further enhance the value and applications of the experiment, and enable derivation of hitherto impossible information.