Abraham N G, Lin J H, Dunn M W, Schwartzman M L
Invest Ophthalmol Vis Sci. 1987 Sep;28(9):1464-72.
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.
在人角膜上皮中证实存在血红素加氧酶和NADPH细胞色素P - 450（c）还原酶，后者是血红素加氧酶和细胞色素P - 450依赖性药物代谢酶的一个组成部分。我们首次报道人角膜上皮中血红素加氧酶活性高达人肝脏所报道活性的20%。使用免疫技术，我们证明人角膜和肝脏中的血红素加氧酶蛋白非常相似；通过蛋白质印迹分析显示两者分子量均为32,000。我们还研究了NADPH细胞色素P - 450（c）还原酶的存在情况。人角膜上皮含有大量的NADPH细胞色素P - 450（c）还原酶活性，并且这种角膜蛋白与已知的肝脏蛋白相似；两者分子量均为71,000，并且能与针对纯化的肝脏NADPH细胞色素P - 450（c）还原酶制备的抗体发生反应。由于血红素加氧酶系统是血红素降解的限速步骤，该系统在角膜上皮细胞血红素的调节中起关键作用，从而调节诸如过氧化氢酶、色氨酸吡咯酶和血栓素合成酶等血红蛋白的活性。
