Presence of heme oxygenase and NADPH cytochrome P-450 (c) reductase in human corneal epithelium.
The presence of heme oxygenase and NADPH cytochrome P-450 (c) reductase, the latter an integral component of heme oxygenase and cytochrome P-450-dependent drug metabolizing enzymes, was demonstrated in human corneal epithelium. We reported for the first time that human corneal epithelium contains heme oxygenase activity as high as 20% of that reported for the human liver. Using immunological techniques, we demonstrated that heme oxygenase proteins from human cornea and liver are very similar; both have a molecular weight of 32,000 as demonstrated by Western blot analysis. We also studied the presence of NADPH cytochrome P-450 (c) reductase. The human corneal epithelium contains significant amount of NADPH cytochrome P-450 (c) reductase activity, and this corneal protein is similar to the known liver protein; both have a molecular weight of 71,000 and react with antibodies prepared against purified liver NADPH cytochrome P-450 (c) reductase. As the heme oxygenase system is the rate limiting step in heme degradation, this system plays a pivotal role in regulation of cellular heme in corneal epithelium, thus modulating the activity of hemoproteins such as catalase, tryptophan pyrrolase and thromboxane synthetase.
D000818:Animals; D002417:Cattle; D003315:Cornea / Q000201:enzymology* / Q000378:metabolism; D004848:Epithelium / Q000201:enzymology / Q000378:metabolism; D005136:Eye Proteins / Q000378:metabolism; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism*; D006801:Humans; D007158:Immunologic Techniques; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism*
D005136:Eye Proteins; D006899:Mixed Function Oxygenases; D006419:Heme Oxygenase (Decyclizing); D009251:NADPH-Ferrihemoprotein Reductase