Modeling the metal center of Cys4 zinc proteins

We present here a 67Zn solid-state NMR investigation of several model complexes of zinc coordinated by four sulfurs. The lineshapes were obtained at a variety of magnetic fields from 11.7 T (500 MHz for 1H) to 21.15 T (900 MHz for 1H) and at ambient temperature down to 10 K. The quadrupole coupling constants, Cq's, ranged from 3.25 to 16.7 MHz throughout the series, while the average bond distances only spanned 2.34-2.36 A. Reasonable agreement with experiment was achieved in the molecular orbital calculations using DFT methods and the local density approximation to predict electric field gradients.