5Y2S

7.0 atm CO2-pressurized human carbonic anhydrase II

Summary for 5Y2S

• Entry DOI: 10.2210/pdb5y2s/pdb
• Related: 5Y2R
• Descriptor: Carbonic anhydrase 2, ZINC ION, CARBON DIOXIDE, ... (5 entities in total)
• Functional Keywords: intermediate states, lyase
• Biological source: Homo sapiens (Human)
• Cellular location: Cytoplasm : P00918
• Total number of polymer chains: 1
• Total formula weight: 29534.59

Authors

Kim, C.U.,Park, S.Y. (deposition date: 2017-07-27, release date: 2018-02-14, Last modification date: 2023-11-22)

Primary citation

Kim, J.K.,Lomelino, C.L.,Avvaru, B.S.,Mahon, B.P.,McKenna, R.,Park, S.,Kim, C.U.
Active-site solvent replenishment observed during human carbonic anhydrase II catalysis.
IUCrJ, 5:93-102, 2018

PubMed Abstract: Human carbonic anhydrase II (hCA II) is a zinc metalloenzyme that catalyzes the reversible hydration/dehydration of CO/HCO. Although hCA II has been extensively studied to investigate the proton-transfer process that occurs in the active site, its underlying mechanism is still not fully understood. Here, ultrahigh-resolution crystallographic structures of hCA II cryocooled under CO pressures of 7.0 and 2.5 atm are presented. The structures reveal new intermediate solvent states of hCA II that provide crystallographic snapshots during the restoration of the proton-transfer water network in the active site. Specifically, a new intermediate water (W') is observed next to the previously observed intermediate water W, and they are both stabilized by the five water molecules at the entrance to the active site (the entrance conduit). Based on these structures, a water network-restructuring mechanism is proposed, which takes place at the active site after the nucleophilic attack of OH on CO. This mechanism explains how the zinc-bound water (W) and W1 are replenished, which are directly responsible for the reconnection of the His64-mediated proton-transfer water network. This study provides the first 'physical' glimpse of how a water reservoir flows into the hCA II active site during its catalytic activity.

PubMed: 29354275
DOI: 10.1107/S2052252517017626

Experimental method

X-RAY DIFFRACTION (0.9 Å)