Apo-human carbonic anhydrase II revisited: implications of the loss of a metal in protein structure, stability, and solvent network

The important role of zinc towards the structural stability of human carbonic anhydrase II (HCA II) which is a monomeric zinc-containing metalloenzyme that catalyzes the hydration of C[O.sub.2] to form bicarbonate and a proton is reported. The results suggested that removal of zinc from the active site have no effect on either the topological fold of the enzyme or the ordered water network in the active site but altered the collective electrostatics of the apo-HCA II.