Peroxidasin: Structure and Function

Peroxidasin (PXDN) belongs to the peroxidase-cyclooxygenase superfamily, along with myeloperoxidase (MPO), eosinophil peroxidase (EPO), lactoperoxidase (LPO), and thyroid peroxidase (TPO). PXDN was originally identified in Drosophila melanogaster in 1994, but research on the enzyme has intensified only during the past decade. The PXDN research field was stimulated by the discovery that PXDN is a crucial enzyme in the synthesis of basement membranes. The enzyme catalyzes the covalent cross-linking of collagen IV through the formation of sulfilimine bonds. The identification of hypobromous acid (HOBr) as the oxidizing compound in the cross-linking reaction provided the first evidence for a physiological role of bromine. Since basement membranes are present in nearly all animal tissues, the discovery of PXDN’s fundamental biochemical function provides compelling evidence for the physiological role of reactive oxygen species in maintaining homeostasis. In this chapter, we review structural and functional studies on PXDN, which shaped our knowledge of this unique enzyme.