Active-site solvent replenishment observed during human carbonic anhydrase II catalysis.

ABSTRACT: Human carbonic anhydrase II (hCA II) is a zinc metalloenzyme that catalyzes the reversible hydration/dehydration of CO₂/HCO₃^-. 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 CO₂ 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_I') is observed next to the previously observed intermediate water W_I, and t

SUBMITTER: Kim JK 

PROVIDER: S-EPMC5755581 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature