FeSOD

FeSOD stands for iron-containing superoxide dismutase, a metalloenzyme that protects cells from reactive oxygen species by catalyzing the dismutation of the superoxide radical (O2−) into molecular oxygen (O2) and hydrogen peroxide (H2O2). It is one of the Fe/Mn SOD family enzymes, existing alongside MnSOD, with Cu/Zn SOD forming a separate family. FeSODs are commonly found in bacteria and archaea and, in some organisms, in plants.

In terms of structure, FeSOD enzymes are typically dimeric or tetrameric and share a common fold with MnSODs, but they differ in the metal cofactor and certain sequence motifs. The iron in the active site is coordinated by conserved ligands, usually histidine and aspartate residues, plus a bound solvent molecule that participates in catalysis. The precise arrangement of these ligands enables efficient redox cycling of the iron between Fe3+ and Fe2+ during turnover.

The catalytic cycle involves two sequential reactions with superoxide. Step one: Fe3+ accepts an electron from O2− to form Fe2+ and O2 is released. Step two: Fe2+ donates an electron to another O2− in the presence of protons, regenerating Fe3+ and producing H2O2. Net reaction: 2 O2− + 2 H+ → H2O2 + O2. This rapid dismutation minimizes oxidative damage to cellular components.

Localization and regulation vary by organism. In bacteria, FeSOD can be cytosolic or periplasmic and is typically encoded by sodB. Expression can be influenced by metal availability and oxidative stress. FeSODs are sometimes studied as potential drug targets in pathogenic bacteria and as models for metal homeostasis and stress responses in microbes.