Verdoheme formation in Proteus mirabilis catalase.

Background: Heme oxidative degradation has been extensively investigated in peroxidases but not in catalases. The verdoheme formation, a product of heme oxidation which inactivates the enzyme, was studied in Proteus mirabilis catalase.

Methods: The verdoheme was generated by adding peracetic acid and analyzed by mass spectrometry and spectrophotometry.

Respective role of uraemic toxins and myeloperoxidase in the uraemic state.

Background: In haemodialysis (HD) patients, advanced oxidation protein products (AOPP) were previously ascribed to oxidized plasma proteins, resulting mainly from increased myeloperoxidase (MPO) activity. The aim of the present study was to assess the mechanisms leading to the generation of AOPP during the course of chronic kidney disease including end-stage renal disease, with particular focus on AOPP and MPO characterization in the plasma at decreasing levels of kidney function.

Methods: Phagocyte activation was evaluated by whole blood NADPH oxidase and MPO activities.

Reduction of ferric haemoproteins by tetrahydropterins: a kinetic study.

We previously showed that one-electron transfer from tetrahydropterins to iron porphyrins is a very general reaction, with formation of an intermediate cation radical similar to the one detected in NO synthase. As a model reaction, the rates of reduction of eight haemoproteins by diMePH4 (6,7-dimethyltetrahydropterin) have been studied and correlated with their one-electron reduction potentials, E(m) (Fe(III)/Fe(II)). On the basis of kinetic data analyses, a bimolecular collisional mechanism is proposed for the electron transfer from diMePH4 to ferrihaemoproteins.

Biochemical and spectrophotometric significance of advanced oxidized protein products.

We previously described the presence of advanced oxidation protein products (AOPP), a novel marker of oxidative stress in the plasma of hemodialyzed patients (HD). The present study was carried out to further investigate how myeloperoxidase (MPO)-catalyzed reactions could contribute to AOPP generation in the plasma. First, patterns of plasma protein oxidation obtained after in vitro incubation of control plasma with hypochlorous acid (HOCl) were compared to those from HD patients and control plasma.

Oxidation of Cu, Zn-superoxide dismutase by the myeloperoxidase/hydrogen peroxide/chloride system: functional and structural effects.

This study investigated the functional and structural effects of bovine Cu, Zn-superoxide dismutase (Cu, Zn-SOD) oxidation by the myeloperoxidase (MPO)/hydrogen peroxide (H2O2)/chloride system and reagent hypochlorous acid (HOCl). Exposure to HOCl led to a fast inactivation accompanied by structural alterations. The residual SOD activity depended on the reactants concentration ratio and on the exposure time.