Reference: Hart,
et al. (1999) A Structure-Based Mechanism for
Copper-Zinc Superoxide Dismutase, Biochemistry 38, 2167-2178.
Zn (4-coordinate): His71, ND, 2.158
His80, ND, 2.108
His 63, ND, 1.942
Asp83 (monodentate), 1.895
Cu (4-coordinate): His120, NE, 2.005
His46, ND, 2.055
His48, NE, 2.241
His63, NE, 2.733 (larger distance b/c this
crystal captures a particular moment in which His63 is closer to the Zn
ion; it shifts back and forth)