Løvstad R A
Department of Medical Biochemistry, University of Oslo, Norway.
Biometals. 1995 Oct;8(4):328-31. doi: 10.1007/BF00141606.
Ascorbate is catalytically oxidized by a couple iron-ceruloplasmin system, the iron ions functioning as a red/ox cycling intermediate between ceruloplasmin and ascorbate. Serum albumin, an iron binding compound, was found to stimulate the ascorbate oxidation rate. It is proposed that ferrous ions react more rapidly with ceruloplasmin when they are bound to albumin. A Km value of 39 microM was estimated for Fe(2+)-albumin. Citrate and urate inhibit the iron-ceruloplasmin-dependent ascorbate oxidation by chelating ferric ions. In the presence of albumin only citrate reduced the oxidation rate, the observation suggesting the following order of iron binding ability: citrate > albumin > urate. Physiological aspects of the results have been discussed.
抗坏血酸盐被铁 - 铜蓝蛋白系统催化氧化，铁离子作为铜蓝蛋白和抗坏血酸盐之间的氧化还原循环中间体发挥作用。血清白蛋白是一种铁结合化合物，被发现可刺激抗坏血酸盐的氧化速率。有人提出，亚铁离子与白蛋白结合时与铜蓝蛋白的反应更快。估计Fe(2 +)-白蛋白的Km值为39 microM。柠檬酸盐和尿酸盐通过螯合铁离子抑制铁 - 铜蓝蛋白依赖性抗坏血酸盐氧化。仅在白蛋白存在的情况下，柠檬酸盐会降低氧化速率，这一观察结果表明铁结合能力的顺序如下：柠檬酸盐>白蛋白>尿酸盐。已讨论了这些结果的生理学方面。
