A QM/MM approach to interpreting 67Zn solid-state NMR data in zinc proteins.

We present here a (67)Zn solid-state NMR investigation of Zn(2+) substituted rubredoxin. The sample has been prepared as both a dry powder and a frozen solution to determine the effects of static disorder on the NMR line shape. Low-temperature experiments have been performed at multiple fields to determine the relative contributions to the NMR line shape from the electric field gradient and the anisotropic shielding tensors. Finally we present the theoretical interpretation of the experimental results utilizing a combined quantum mechanical molecular mechanics (QM/MM) approach. Theory predicts a sizable contribution from anisotropic shielding as compared with previously examined model systems. This is in good agreement with the experimental data.