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

Abstract

Pseudocontact shifts (PCSs) provide valuable structural and dynamic information in (large) proteins. We pro- pose 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 measure- ment of six PCSs corresponding to 1 H N , 1 H  , 13 C  , 13 C  , 13 C' and 15 N 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 multi- ple 3D correlation experiments. The utility of the proposed experiments is demonstrated with an 8.5 kDa protein, Cal- bindin. 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.