Gutteridge J M, Quinlan G J
Department of Anaesthesia and Intensive Care, Royal Brompton Hospital, London, UK.
Biochim Biophys Acta. 1992 Oct 20;1159(3):248-54. doi: 10.1016/0167-4838(92)90052-f.
Normal human plasma contains numerous high- and low-molecular-mass redox-active molecules that are able to react rapidly with organic and inorganic oxygen radicals. The ability of such plasma molecules to substantially inhibit, or delay, free-radical mediated oxidation of added substrates has led to their classification as important biological antioxidants. Using phospholipids to detect organic oxygen radicals and deoxyribose to detect inorganic oxygen radicals, we here show that the primary antioxidants of normal human plasma reside mainly in two plasma proteins representing no more than 4% of the total proteins present. The iron-binding properties of transferrin and the iron-oxidising properties of caeruloplasmin, at a reaction dilution of 1:50, offer considerable protection against organic and inorganic oxygen radicals generated by iron and ascorbate. Plasma thiol-group-containing molecules, at concentrations well below those that would be required to compete with the detector molecule (based on known second-order rate constants for reaction with hydroxyl radicals) inhibited damage to deoxyribose, but stimulated damage to phospholipids.
正常人体血浆含有众多高、低分子量的氧化还原活性分子，这些分子能够与有机和无机氧自由基迅速反应。此类血浆分子能显著抑制或延缓添加底物的自由基介导氧化，这使得它们被归类为重要的生物抗氧化剂。利用磷脂检测有机氧自由基，用脱氧核糖检测无机氧自由基，我们在此表明，正常人体血浆的主要抗氧化剂主要存在于两种血浆蛋白中，这两种蛋白占血浆中总蛋白的比例不超过4%。在1:50的反应稀释度下，转铁蛋白的铁结合特性和铜蓝蛋白的铁氧化特性，能为抵御铁和抗坏血酸产生的有机和无机氧自由基提供相当程度的保护。血浆中含巯基的分子，其浓度远低于与检测分子竞争所需的浓度（基于与羟基自由基反应的已知二级速率常数），可抑制对脱氧核糖的损伤，但会促进对磷脂的损伤。
