The ins and outs of biological zinc sites

The inner shell coordination properties of zinc proteins have led to the identification of four types of zinc binding sites: catalytic, cocatalytic, structural, and protein interface. Outer shell coordination can influence the stability of the zinc site and its function as exemplified herein by the zinc sites in carbonic anhydrase, promatrix metalloproteases and alcohol dehydrogenase. Agents that disrupt these interactions, can lead to increased off rate constants for zinc. d-penicillamine is the first drug to inhibit a zinc protease by catalyzing the removal of the metal. Since it can accept the released zinc we have referred to it as a catalytic chelator. Agents that catalyze the release of the metal in the presence of a scavenger chelator will also inhibit enzyme catalysis and are referred to as enhanced dechelation inhibitors.