Membrane-Bound Flavocytochrome MsrQ Is a Substrate of the Flavin Reductase Fre in .

MsrPQ is a new type of methionine sulfoxide reductase (Msr) system found in bacteria. It is specifically involved in the repair of periplasmic methionine residues that are oxidized by hypochlorous acid. MsrP is a periplasmic molybdoenzyme that carries out the Msr activity, whereas MsrQ, an integral membrane-bound hemoprotein, acts as the physiological partner of MsrP to provide electrons for catalysis.

Conformational H-bonding modulation of the iron active site cysteine ligand of superoxide reductase: absorption and resonance Raman studies.

Superoxide reductases (SORs) are mononuclear non-heme iron enzymes involved in superoxide radical detoxification in some microorganisms. Their atypical active site is made of an iron atom pentacoordinated by four equatorial nitrogen atoms from histidine residues and one axial sulfur atom from a cysteinate residue, which plays a central role in catalysis. In most SORs, the residue immediately following the cysteinate ligand is an asparagine, which belongs to the second coordination sphere and is expected to have a critical influence on the properties of the active site.

Iron Hydroperoxide Intermediate in Superoxide Reductase: Protonation or Dissociation First? MM Dynamics and QM/MM Metadynamics Study.

Superoxide reductase is a mononuclear iron enzyme involved in superoxide radical detoxification in some bacteria. Its catalytic mechanism is associated with the remarkable formation of a ferric hydroperoxide Fe-OOH intermediate, which is specifically protonated on its proximal oxygen to generate the reaction product HO. Here, we present a computational study of the protonation mechanism of the Fe-OOH intermediate, at different levels of theory.

A Two-component NADPH Oxidase (NOX)-like System in Bacteria Is Involved in the Electron Transfer Chain to the Methionine Sulfoxide Reductase MsrP.

MsrPQ is a newly identified methionine sulfoxide reductase system found in bacteria, which appears to be specifically involved in the repair of periplasmic proteins oxidized by hypochlorous acid. It involves two proteins: a periplasmic one, MsrP, previously named YedY, carrying out the Msr activity, and MsrQ, an integral b-type heme membrane-spanning protein, which acts as the specific electron donor to MsrP. MsrQ, previously named YedZ, was mainly characterized by bioinformatics as a member of the FRD superfamily of heme-containing membrane proteins, which include the NADPH oxidase proteins (NOX/DUOX).

Non-heme iron hydroperoxo species in superoxide reductase as a catalyst for oxidation reactions.

The non-heme high-spin ferric iron hydroperoxo species formed in superoxide reductase catalyzes oxidative aldehyde deformylation through its nucleophilic character. This species also acts as an electrophile to catalyze oxygen atom transfer in sulfoxidation reactions, highlighting the oxidation potential of non-heme iron hydroperoxo species.