Myeloperoxidase is an enzyme that can use hydrogen peroxide to oxidize chloride, forming hypochlorous acid. The enzyme occurs in neutrophils and other immune cells, where its oxidant chemistry contributes to antimicrobial activity. One balanced representation of the reaction is:The equation identifies consumed reactants and product; the enzyme itself is regenerated during catalysis.[ref]
A protein's catalytic reaction does not exhaust its possible biological roles. A 2010 study found that myeloperoxidase enhanced chromatin decondensation together with neutrophil elastase, with the enhancement independent of myeloperoxidase's enzymatic activity in the tested system.[ref]
Neutrophil elastase and myeloperoxidase regulate the formation of neutrophil extracellular traps by Venizelos Papayannopoulos and others. Abstract and Fig. 1H, cooperative effect on isolated nuclei
This provides a useful experimental distinction: removing a protein and selectively disabling one catalytic activity need not have identical consequences. To assign a phenotype to oxidant production, an experiment must test that chemistry rather than infer it solely from the presence or absence of myeloperoxidase.
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