The figure below displays the electrostatic potential of the enzyme Cu,Zn superoxide dismutase. The electric field steers diffusing substrate into the active site, speeding the action of the enzyme. Based on work at SDSC by Michael Potter, of J.A. McCammon's group at UCSD. The crystal structure of the enzyme was determined by Elizabeth Getzoff's research group at TSRI. Image created using InsightII and UHBD from Molecular Simulations, Inc., San Diego CA