Peroxidase activity of oxyhaemoglobin in vitro

Abstract

1. In bovine erythrocyte suspensions incubated with 16mM aniline, 4-phenetidine, 4-chloro- or 3,4-dichloroaniline for three hours at 37°C, HbFe³⁺ concentrations of 10, 35, 77 and 93%, respectively, were found.

2. N- and C-oxygenation products of aniline, 4-chloro-, and 3,4-dichloroaniline were formed, which can explain the oxidation of HbFe³⁺, indicative of peroxygenase activity of oxyhaemoglobin.

3. The same N- and C-oxygenated derivatives of 4-chloro- and 3,4-dichloroaniline were also formed by hepatic microsomes, although at a 25- to 5000-fold higher rate.

4. HbFe³⁺ was formed more readily on incubation of either bovine erythrocytes or purified human Hb with various N-arylacetohydroxamic acids.

5. The metabolites of N-(4-chlorophenyl)-N-hydroxyacetamide are the same as the products of chemical oxidation of NOH-4C1AA by PbO₂ or KMnO₄, indicating the peroxidase activity of oxyhaemoglobin.