A myeloperoxidase precursor, pro-myeloperoxidase, is present in human plasma and elevated in cardiovascular disease patients.

Myeloperoxidase (MPO)-derived oxidants have emerged as a key contributor to tissue damage in inflammatory conditions such as cardiovascular disease. Pro-myeloperoxidase (pro-MPO), an enzymatically active precursor of myeloperoxidase (MPO), is known to be secreted from cultured bone marrow and promyelocytic leukemia cells, but evidence for the presence of pro-MPO in circulation is lacking. In the present study, we used a LC-MS/MS in addition to immunoblot analyses to show that pro-MPO is present in human blood plasma.

Uric acid and thiocyanate as competing substrates of lactoperoxidase.

The physiological function of urate is poorly understood. It may act as a danger signal, an antioxidant, or a substrate for heme peroxidases. Whether it reacts sufficiently rapidly with lactoperoxidase (LPO) to act as a physiological substrate remains unknown.

Myeloperoxidase and oxidation of uric acid in gout: implications for the clinical consequences of hyperuricaemia.

Objectives: The aims of this study were to establish whether, in patients with gout, MPO is released from neutrophils and urate is oxidized to allantoin and if these effects are attenuated by allopurinol.

Methods: MPO, urate, allantoin and oxypurinol were measured in plasma from 54 patients with gout and 27 healthy controls. Twenty-three patients had acute gout, 13 of whom were receiving allopurinol, and 31 had intercritical gout, 20 of whom were receiving allopurinol.

Oxidation contributes to low glutathione in the airways of children with cystic fibrosis.

Glutathione is an important antioxidant in the lungs but its concentration is low in the airways of patients with cystic fibrosis. Whether this deficit occurs from an early age or how oxidative stress contributes to lowering glutathione is unknown. We measured glutathione, its oxidation products, myeloperoxidase, and biomarkers of hypochlorous acid in bronchoalveolar lavage from children with cystic fibrosis and disease controls using mass spectrometry and immunological techniques.