Enzymatic oxidation and reduction of retinal by mouse epidermis

Evidence is presented for the ability of mouse epidermis to oxidize retinal by the action of a cytosolic enzyme with a pH optimum of about 8.5. The enzyme activity was slightly enhanced by the addition of either NAD or FAD. The reaction exhibited Michaelis-Menton kinetics with a km of 1.627 × 10^?4M for retinal. Mouse epidermal cytosol was also capable of reducing retinal. This enzyme had an optimum pH of 6.0 and the activity of the undialyzed enzyme was enhanced 5- to 7-fold by the addition of reduced NAD or NADP. Possible roles of these enzymic activities in epidermis are discussed.