Quiescin sulfhydryl oxidase from Trypanosoma brucei: catalytic activity and mechanism of a QSOX family member with a single thioredoxin domain.

ABSTRACT: Quiescin sulfhydryl oxidase (QSOX) flavoenzymes catalyze the direct, facile, insertion of disulfide bonds into reduced unfolded proteins with the reduction of oxygen to hydrogen peroxide. To date, only QSOXs from vertebrates have been characterized enzymatically. These metazoan sulfhydryl oxidases have four recognizable domains: a redox-active thioredoxin (Trx) domain containing the first of three CxxC motifs (C(I)-C(II)), a second Trx domain with no obvious redox-active disulfide, a helix-rich domain, and then an Erv/ALR domain. This last domain contains the FAD moiety, a proximal C(III)-C(IV) disulfide, and a third CxxC of unknown function (C(V)-C(VI)). Plant and protist QSOXs lack the second Trx domain but otherwise appear to contain the same complement of redox centers. This work prese

SUBMITTER: Kodali VK 

PROVIDER: S-EPMC2831140 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature