COMPARISON OF PEROXIDASES IN THE RETINA, CHOROID AND RED-BLOOD-CELLS

Most of the peroxidase activity in the bovine retina is specific to gl utathione (GSH) while the choroid contains both GSH peroxidases and as corbate peroxidase. The GSH peroxidase was clearly separated from asco rbate peroxidase on a cation exchange column. The nonspecific peroxida se activity of hemoproteins accounts for the peroxidase activity detec ted by ascorbate oxidation. All choroidal hemoproteins contain subunit s very similar to those of hemoglobin. The absence of ascorbate peroxi dase in the retina indicates that the protective effect of ascorbate a gainst photic injury is not due to its reaction with retinal peroxidas e. Therefore removal of H2O2 by ascorbate peroxidase activity in the c horoid could be a significant factor in studies where serum ascorbate concentrations are artificially raised far above the normal level conc urrent to a very small rise in retinal ascorbate concentration.