The contribution of GSH peroxidase-1, catalase and GSH to the degradation of H2O2 by the mouse lens

Abstract

Utilizing cultured lenses from normal and homozygous glutathione peroxidase (GSHPx-1) knockout mice and inhibitors for GSSG Reductase (GSSG Red), 1,3-bis(2-chlorethyl)-1-nitrosourea (BCNU) and catalase (Cat), 3-aminotriazole (3-AT), the ability to degrade H2O2, was examined at two H2O2 concentrations, 300 μM and 80 μM. It was found that GSHPx-1 contributed about 15% to the H2O2 degradation. The Cat contribution was concentration dependent being about 30% at 300 μM H2O2 and approximately 8% to 15% at 80 μM H2O2. GSH loss measured as nonprotein thiol (NP-SH) was shown to be linked to most of the remaining H2O2 degradation accounting for about 54% to 72% of the H2O2 degradation at 300 μM and 80 μM, respectively. However, based on evaluation of the ability of GSH to nonenzymatically degrade H2O2, it can only account for about 36% at 300 μM and 19% at 80 μM H2O2 of the observed lens H2O2 degradation. It is, therefore, concluded that lens GSH must be involved in other reactions either directly or indirectly related to H2O2 degradation.