The Regenerative System for Proteins inactivated by Oxidative Stress in Cardiovascular System

本研究以培养的内皮细胞和全心脏为材料，研究了蛋白巯基/二硫键交换酶（如硫氧还蛋白、硫氧还蛋白还原酶、谷氧还蛋白和蛋白二硫键异构酶）作为氧化应激失活蛋白的再生（或修复）系统。硫氧还蛋白、硫氧还蛋白还原酶、谷氧还蛋白和蛋白质二硫键异构酶参与了内皮细胞氧化应激失活蛋白的再生反应.硫氧还蛋白和谷氧还蛋白在氧化损伤蛋白的再生反应中表现出不同的底物特异性.氧化应激可增加血管内皮细胞和整个心脏中硫氧还蛋白和蛋白质二硫键异构酶的蛋白水平.克隆人谷氧还蛋白cDNA.硫氧还蛋白和硫氧还蛋白还原酶被发现定位于细胞质和线粒体组分的牛心脏。这些酶从每个隔室中分离。硫氧还蛋白/硫氧还蛋白还原酶系统对一氧化氮介导的线粒体呼吸活性抑制具有保护作用，表明这些蛋白质巯基/二硫键交换酶，尤其是硫氧还蛋白/硫氧还蛋白还原酶系统作为氧化损伤蛋白的内源性再生系统，在细胞抗氧化防御机制中发挥重要作用。

Protein thiol/disulfide exchanging enzymes such as thioredoxin, thioredocin reductase, glutaredoxin and protein disulfide isomerase were studied as a regenerative (or repair) system for proteins inactivated by oxidative stress using cultured endothelial cells and whole hearts.The results obtained in this study were ;1. Thioredoxin, thioredoxin reductase, glutaredoxin and protein disulfide isomerase were involved in the regeneration reaction of proteins inactivated by oxidative stress in endothelial cells.2. Thioredoxin and glutaredoxin exhibited the different substrate specificity in the regeneration reaction of the oxidatively-damaged proteins.3. The protein levels of thioredoxin and protein disulfide isomerase in vascular endothelial cells and whole hearts were increased by exposure to oxidative stress.4. Human glutaredoxin cDNA was cloned.5. Thioredoxin and thioredoxin reductase were found to be localized in both cytosol and mitochondrial fractions of bovine heart. These enzymes were isolated from each compartment.6. Thioredoxin/thioredoxin reductase system was found to exert a protective effect on the nitric oxidemediated inhibition of mitochondrial respiratory activity.These findings indicated that these protein thiol/disulfide exchanging enzymes, especially thioredoxin/thioredoxin reductase system playd an important role in the cellular antioxidant defense mechanism by functioning as an endogenous regeneration system for oxidatively-damaged proteins.