DEHYDROASCORBATE REDUCTASE-ACTIVITY IN BOVINE LENS

The bovine lens was studied for the presence of-dehydroascorbate reduc tase activity. The activity was found to be restricted primarily to th e mitochondrial fraction isolated from the cortex-epithelial fraction of the tissue. It was not detectable in the cytosolic fraction. The K- m of reaction with dehydroascorbate was approximate to 0.45 mM. These studies suggest that the reduction of dehydroascorbate to ascorbate in the mitochondria takes place enzymatically as well as nonenzymaticall y, GSH being the source of reducing electrons in both the cases. The e nzymatic mechanism may assume a greater role in situations of oxidativ e stress which lead to GSH depletion. The presence of this enzyme in t he mitochondria is considered with a normally more severe oxidative co ndition therein.