@entity165 oxidase (CO) is a flavoenzyme that catalyzes the oxidation and isomerization of @entity165 to @entity64410 . The reductive half reaction occurs via a @entity7470 transfer from the substrate to the FAD cofactor. The structures of CO reduced with @entity6857 under aerobic conditions and in the presence of the substrate @entity5723 under both aerobic and anaerobic conditions are presented. The 1.32      resolution structure of the @entity6857 -reduced enzyme reveals a @entity9735 molecule covalently bound to the FAD cofactor. The @entity21171 ring system displays a bent structure relative to that of the oxidized enzyme, and alternate conformations of a triad of aromatic residues near to the cofactor are evident. A 1.12      resolution anaerobically trapped reduced enzyme structure in the presence of @entity5723 does not show a similar bending of the @entity1785 ring system, but does show alternate conformations of the aromatic triad. Additionally, a significant difference electron-density peak is observed within a covalent-bond distance of N5 of the @entity1785 moiety, suggesting that a @entity7470 -transfer event has occurred as a result of substrate oxidation trapping the @entity1785 in the electron-rich reduced state. The @entity7470 transfer generates a tetrahedral geometry about the flavin N5 atom. High-level density-functional theory calculations were performed to correlate the crystallographic findings with the energetics of this unusual arrangement of the @entity1785 moiety. These calculations suggest that strong @entity3884 -bond interactions between @entity4022 120 and the @entity1785 N5 centre may play an important role in these structural features.

High-resolution structures of XXXX oxidase in the reduced state provide insights into redox stabilization.

@entity3884 :: ('MESH:D006859', 'Chemical') :: ['hydrogen'] @entity1785 :: ('MESH:C024132', 'Chemical') :: ['flavin'] @entity7470 :: ('CHEBI:29239', 'Chemical') :: ['hydride'] @entity9735 :: ('CHEBI:48854', 'Chemical') :: ['sulfite'] @entity4022 :: ('MESH:C066286', 'Chemical') :: ['Gly'] @entity21171 :: ('MESH:C008173', 'Chemical') :: ['isoalloxazine'] @entity6857 :: ('MESH:D004227', 'Chemical') :: ['dithionite'] @entity64410 :: ('MESH:C000475', 'Chemical') :: ['cholest-4-en-3-one'] @entity5723 :: ('MESH:D019840', 'Chemical') :: ['2-propanol'] @entity165 :: ('MESH:D002784', 'Chemical') :: ['Cholesterol', 'cholesterol']
@entity165 :: (MESH:D002784,Chemical) :: ['cholesterol']
