Animal heme-dependent peroxidases
| Animal heme-dependent peroxidase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
Crystal structure of the human myeloperoxidase-thiocyanate complex.
|
|||||||||
| Identifiers | |||||||||
| Symbol | An_peroxidase | ||||||||
| Pfam | PF03098 | ||||||||
| InterPro | IPR002007 | ||||||||
| PROSITE | PDOC00394 | ||||||||
| SCOP | 1mhl | ||||||||
| SUPERFAMILY | 1mhl | ||||||||
| OPM superfamily | 37 | ||||||||
| OPM protein | 1q4g | ||||||||
| CDD | cd05396 | ||||||||
|
|||||||||
| Available protein structures: | |
|---|---|
| Pfam | structures |
| PDB | RCSB PDB; PDBe; PDBj |
| PDBsum | structure summary |
Animal heme-dependent peroxidases is a family of peroxidases.
Peroxidases are found in bacteria, fungi, plants and animals. On the basis of sequence similarity, a number of animal heme peroxidases can be categorized as members of a superfamily: myeloperoxidase (MPO); eosinophil peroxidase (EPO); lactoperoxidase (LPO); thyroid peroxidase (TPO); prostaglandin H synthase (PGHS); and peroxidasin.
Myeloperoxidase (MPO) plays a major role in the oxygen-dependent microbicidal system of neutrophils. EPO from eosinophilic granulocytes participates in immunological reactions, and potentiates tumor necrosis factor (TNF) production and hydrogen peroxide release by human monocyte-derived macrophages. MPO (and possibly EPO) primarily use Cl−ions and H2O2 to form hypochlorous acid (HOCl), which can effectively kill bacteria or parasites. In secreted fluids, LPO catalyses the oxidation of thiocyanate ions (SCN−) by H2O2, producing the weak oxidizing agent hypothiocyanite (OSCN−), which has bacteriostatic activity. TPO uses I− ions and H2O2 to generate iodine, and plays a central role in the biosynthesis of thyroid hormones T3 and T4. Myeloperoxidase (PDB: 1dnu), for example, resides in the human nucleus and lysosome and acts as a defense response to oxidative stress, preventing apoptosis of the cell.
3D structures of MPO and PGHS have been reported. MPO is a homodimer: each monomer consists of a light (A or B) and a heavy (C or D) chain resulting from post-translational excision of 6 residues from the common precursor. Monomers are linked by a single inter-chain disulfide. Each monomer includes a bound calcium ion. PGHS exists as a symmetric dimer, each monomer of which consists of 3 domains: an N-terminal epidermal growth factor (EGF) like module; a membrane-binding domain; and a large C-terminal catalytic domain containing the cyclooxygenase and the peroxidase active sites. The catalytic domain shows striking structural similarity to MPO. The image at the top of this page is an example of Myeloperoxidase 1dnu derived from X-ray diffraction with resolution 1.85 angstrom.
...
Wikipedia