BACKGROUND In vitro and animal studies demonstrate that myeloperoxidase catalytically consumes nitric oxide as a substrate, limiting its bioavailability and function. We therefore hypothesized that circulating levels of myeloperoxidase would predict risk of endothelial dysfunction in human subjects. METHODS AND RESULTS Serum myeloperoxidase was measured by enzyme-linked immunoassay, and brach...

Myeloperoxidase is an inflammatory enzyme that generates reactive hypochlorous acid in the presence of hydrogen peroxide and chloride ion. However, this enzyme also uses bromide ion or thiocyanate as a substrate to form hypobromous or hypothiocyanous acid, respectively. These species play important roles in host defense against the invasion of microorganisms. In contrast, these enzyme products ...

background: myeloperoxidase (mpo), which is abundantly expressed in neutrophils, catalyzes the formation of a number of reactive oxidant species. however, evidence has emerged that mpo-derived oxidants contribute to tissue damage and initiation and propagation of inflammatory diseases, particularly, cardiovascular diseases. therefore, studying the regulatory mechanisms of the enzyme activity is...

The neutrophil enzyme myeloperoxidase uses H2O2 to oxidize chloride, bromide, iodide and thiocyanate to their respective hypohalous acids. Chloride is considered to be the physiological substrate. However, a detailed kinetic study of its substrate preference has not been undertaken. Our aim was to establish whether myeloperoxidase oxidizes thiocyanate in the presence of chloride at physiologica...

We have examined the effect of the myeloperoxidase-hydrogen peroxide-halide system and of activated human neutrophils on the ability of serum alpha 1-protease inhibitor (alpha 1-PI) to bind and inhibit porcine pancreatic elastase. Exposure to the isolated myeloperoxidase system resulted in nearly complete inactivation of alpha 1-PI. Inactivation was rapid (10 to 20 s); required active myelopero...

Mice were injected intravenously with Candida albicans blastospores to establish chronic renal infection. Seventy-five percent of the animals inoculated with 10(6) blastospores died as a consequence of infection during the subsequent 60 days of observation. Intraperitoneal administration of 10 mU of partially purified human myeloperoxidase 1 day after injection of the pathogen increased surviva...