Ascorbate peroxidase in bovine retinal pigment epithelium and choroid.
Peroxidase, catalyzing hydrogen peroxide reduction concurrent with ascorbate oxidation, was demonstrated in the extract of retinal pigment epithelium and choroid. The peroxidase in the choroid, RPE, and retina are 236.1, 25.1, and 0.5 units/mg protein respectively. Ammonium sulfate fractionation and high pressure liquid chromatography showed that the peroxidase in the RPE-choroid is associated with a group of heme proteins with absorption maxima at 410 nm, and optimal activity at pH 4.5. The high peroxidase activity in the RPE-choroid explains the observation of dehydroascorbate in these tissues and indicates a possible role of this enzyme in the removal of H2O2.
Department of Ophthalmology, University of Texas Health Science Center, San Antonio 78284.
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D000645:Ammonium Sulfate; D000818:Animals; D060387:Ascorbate Peroxidases; D002417:Cattle; D011232:Chemical Precipitation; D002829:Choroid / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005136:Eye Proteins / Q000032:analysis; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism*; D010857:Pigment Epithelium of Eye / Q000201:enzymology*
D005136:Eye Proteins; D006861:Hydrogen Peroxide; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D000645:Ammonium Sulfate