Rapid Measurement of Pseudocontact Shifts in Paramagnetic Proteins by GFT NMR Spectroscopy

Pseudocontact shifts (PCSs) provide valuable structural and dynamic information in (large) proteins. We propose a methodology based on the principle of G-matrix Fourier transform (GFT) NMR spectroscopy for simultaneous and rapid measurement of a large number of PCSs in proteins with a paramagnetic centre. Four experiments, namely, (3,2)D HNNCO, (3,2)D HNN(CO)CA, (3,2)D HNN(COCA)CB and (3,2)D HNHA taken together facilitate accurate measurement of six PCSs corresponding to 1HN, 1Hα, 13Cα, 13Cβ, 13C' and 15N nuclei. In addition, a new algorithm is presented for unambiguous sequence specific resonance assignments of peaks shifted due to PCS. This avoids the need to record multiple 3D correlation experiments. The utility of the proposed experiments is demonstrated with an 8.5 kDa protein, Calbindin. This provides new avenues to a wide range of applications in structure determination/refinement/verification and dynamical studies of proteins in general and paramagnetic proteins in particular.