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

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), S-aminotriazole (3-AT), the ability to degrade H2O2 was examined at two H2O2 concentrations, 300 mu M and 80 mu M. It was found that GSHPx-1 contributed about 15% to the H2O2 degradation. The Cat contribution was concentration dependent being about 30% at 300 mu M H2O2 and approximately 8% to 15% at 80 mu M 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 mu M and 80 mu M, respectively. However, based on evaluation of the ability of GSH to nonenzymatically degrade H2O2, it can only account for about 36% at 300 mu M and 19% at 80 mu M 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. (C) 1997 Academic Press Limited.