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

ABSTRACT: Human carbonic anhydrase II (HCA II) is a monomeric zinc-containing metalloenzyme that catalyzes the hydration of CO(2) to form bicarbonate and a proton. The properties of the zinc have been extensively elucidated in catalysis but less well studied as a contributor to structure and stability. Apo-HCA II (without zinc) was prepared and compared to holo-HCA II: in crystallographic structural features, in backbone amide H/D exchange, and in thermal stability. The removal of zinc from the active site has no effect on either the topological fold of the enzyme or the ordered water network in the active site. However, the removal of the zinc alters the collective electrostatics of the apo-HCA II that result in the following differences from that of the holoenzyme: (1) the main thermal unfolding t

SUBMITTER: Avvaru BS 

PROVIDER: S-EPMC2762735 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature