Catalyzes the two-electron oxidation of bromide by hydrogen peroxide and generates hypobromite as a reactive intermediate which mediates the formation of sulfilimine cross-links between methionine and hydroxylysine residues within an uncross-linked collagen IV/COL4A1 NC1 hexamer (PubMed:18929642, PubMed:19590037, PubMed:22842973, PubMed:25708780, PubMed:25713063, PubMed:27697841, PubMed:28154175, PubMed:34679700). In turns, directly contributes to the collagen IV network-dependent fibronectin/FN and laminin assembly, which is required for full extracellular matrix (ECM)-mediated signaling (PubMed:19590037, PubMed:32543734, PubMed:34679700). Thus, sulfilimine cross-links are essential for growth factor-induced cell proliferation and survival in endothelial cells, an event essential to basement membrane integrity (PubMed:32543734). In addition, through the bromide oxidation, may promote tubulogenesis and induce angiogenesis through ERK1/2, Akt, and FAK pathways (PubMed:25713063). Moreover brominates alpha2 collagen IV chain/COL4A2 at ‘Tyr-1485’ and leads to bromine enrichment of the basement membranes (PubMed:32571911). In vitro, can also catalyze the two-electron oxidation of thiocyanate and iodide and these two substrates could effectively compete with bromide and thus inhibit the formation of sulfilimine bonds (PubMed:28154175). Binds laminins (PubMed:32485152). May play a role in the organization of eyeball structure and lens development during eye development (By similarity).
