Weak Alignment of Paramagnetic Proteins Warrants Correction for Residual CSA Effects in Measurements of Pseudocontact Shifts

摘要

Paramagnetic metal ions with an anisotropic magnetic susceptibility lambda induce pseudocontact shifts(PCS)that can significantly change the chemical shifts of nuclear spins up to 40 A from the metal ion.PCSs represent a rich source of information for 3D structure determinations and resonance assignments of metallo-proteins as they report on the location of the nuclear spin with respect to the lambda tensor: