The kinetics and mechanism of superoxide reduction by two-iron superoxide reductase from Desulfovibrio vulgaris
Emerson, Joseph Patrick
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Superoxide reductase (SOR) has been recently found in anaerobic bacteria and archaea, and is proposed to be involved in a pathway of oxidative resistance. The sulfate reducing-anaerobic bacterium Desulfovibrio vulgaris expresses an SOR, which contains two non-heme iron centers. A novel [Fe(NHis)4(SCys)] site is proposed to interact with superoxide, and a rubredoxin-like, [Fe(SCys)4] site is presumably involved in electron transfer. In order to better understand the oxidative stress resistance pathway within anaerobic bacteria, a detailed kinetic study of the reaction of the D. vulgaris 2Fe-SOR, along with several engineered variants are studied as they interact with several reactive oxygen species. Identification of a transient species produced from the reaction of SOR with superoxide is described, as well as the kinetics associated with formation and decay are elaborated upon. The role of the [Fe(SCys)4] site is explored by characterization of a [Fe(SCys)4] deficient variant of D. vulgaris 2Fe-SOR.