Predominant role of catalase in the disposal of hydrogen peroxide within human erythrocytes

Abstract

Purified enzymes were mixed to form a cell-free system that simulated the conditions for removal of hydrogen peroxide within human erythrocytes. Human glutathione peroxidase disposed of hydrogen peroxide (H2O2) at a rate that was only 17% of the rate at which human catalase simultaneously removed hydrogen peroxide. The relative rates observed were in agreement with the relative rates predicted from the kinetic constants of the two enzymes. These results confirm two earlier studies on intact erythrocytes, which refuted the notion that glutathione peroxidase is the primary enzyme for removal of hydrogen peroxide within erythrocytes. The present findings differ from the results with intact cells, however, in showing that glutathione peroxidase accounts for even less than 50% of the removal of hydrogen peroxide. A means is proposed for calculating the relative contribution of glutathione peroxidase and catalase in other cells and species. The present results raise the possibility that the major function of glutathione peroxidase may be the disposal of organic peroxides rather than the removal of hydrogen peroxide.

Antioxidant status and lipid peroxidation in the blood of breast cancer patients of different ages after chemotherapy with 5-fluorouracil, doxorubicin and cyclophosphamide

“…26 Since GPx activity in blood cells was unchanged in middle-aged and oldest groups of patients in this work, it seems that oxidative damages caused by decreased capacity for H 2 O 2 elimination is related to suppressed activity of CAT, as well as to suppressed direct AO action of GSH. This is in agreement with previous findings that CAT has a more significant role than GPx in protecting erythrocytes against oxidative stress, 27,28 and that CAT is at least as important as glutathione in cellular defense against H 2 O 2 -mediated damage. 29 The lower GSH level seen in the circulation of breast cancer patients supports the hypothesis that GSH status is inversely related to malignant transformation.…”

Substituting fishmeal with extruded soybean meal in diets did not affect the growth performance, hepatic enzyme activities, but hypoxia tolerance of Dolly Varden (Salvelinus malma) juveniles

“…The total antioxidant capacity (T‐AOC) is a well‐suited indicator of the antioxidant functions (Sheikhzadeh, Tayefi‐Nasrabadi, Oushani, & Enferadi, ), while superoxide dismutase (SOD) and catalase (CAT) are important antioxidant defences for protecting the cell from oxidative damage by reactive oxygen species (ROS) (Gaetani et al, ; Tainer, Getzoff, Richardson, & Richardson, ) and were used in aquaculture researches, such as the response to thermal stress for Onychostoma macrolepis (Yu et al, ) or environmental toxicant for freshwater bivalve (Xia et al, ). The ESBM substituted diets had no effects on the activities of T‐AOC, SOD and CAT, showing no harmful effects on ROS eliminating ability for Dolly Varden juveniles.…”

Increased basal oxidation of peroxiredoxin 2 and limited peroxiredoxin recycling in glucose‐6‐phosphate dehydrogenase‐deficient erythrocytes from newborn infants

“…Several antioxidant pathways use NADPH as the terminal reductant. Although NADPH increases the efficiency of H 2 O 2 removal by catalase (7), the common view is that it is mainly required for removal of peroxides via the glutathione peroxidase/glutathione reductase pathway (8). However, another important class of NADPH-dependent antioxidant enzymes is the peroxiredoxins (9).…”