Department of Biochemistry and Molecular Biology, University of Minnesota Medical School Duluth, USA.
Comp Biochem Physiol C Toxicol Pharmacol. 2010 May;151(4):473-9. doi: 10.1016/j.cbpc.2010.02.005. Epub 2010 Feb 16.
Ceruloplasmin (Cp) is a multicopper oxidase and the most abundant copper binding protein in vertebrate plasma. Loss of function mutations in humans or experimental deletion in mice result in iron overload consistent with a putative ferroxidase function. Prior work suggested plasma may contain multiple ferroxidases. Studies were conducted in Holtzman rats (Rattusnorvegicus), albino mice (Mus musculus), Cp-/- mice, and adult humans (Homo sapiens) to investigate the copper-iron interaction. Dietary copper-deficient (CuD) rats and mice were produced using a modified AIN-76A diet. Results confirmed that o-dianisidine is a better substrate than paraphenylene diamine (PPD) for assessing diamine oxidase activity of Cp. Plasma from CuD rat dams and pups, and CuD and Cp-/- mice contained no detectable Cp diamine oxidase activity. Importantly, no ferroxidase activity was detectable for CuD rats, mice, or Cp-/- mice compared to robust activity for copper-adequate (CuA) rodent controls using western membrane assay. Immunoblot protocols detected major reductions (60-90%) in Cp protein in plasma of CuD rodents but no alteration in liver mRNA levels by qRT-PCR. Data are consistent with apo-Cp being less stable than holo-Cp. Further research is needed to explain normal plasma iron in CuD mice. Reduction in Cp is a sensitive biomarker for copper deficiency.
铜蓝蛋白（Cp）是一种多铜氧化酶，也是脊椎动物血浆中含量最丰富的铜结合蛋白。人类功能丧失突变或实验性敲除小鼠导致铁过载，这与潜在的亚铁氧化酶功能一致。先前的研究表明，血浆中可能含有多种亚铁氧化酶。本研究在霍尔茨曼大鼠（Rattus norvegicus）、白化小鼠（Mus musculus）、Cp-/- 小鼠和成年人类（Homo sapiens）中进行，以研究铜铁相互作用。使用改良的AIN-76A 饮食来制备铜缺乏（CuD）大鼠和小鼠。结果证实邻二茴香胺比对苯二胺（PPD）更适合评估 Cp 的二胺氧化酶活性。CuD 大鼠和小鼠的胎鼠和母鼠的血浆以及 CuD 和 Cp-/- 小鼠的血浆中均未检测到可检测的 Cp 二胺氧化酶活性。重要的是，与铜充足（CuA）啮齿动物对照相比，CuD 大鼠、小鼠或 Cp-/- 小鼠的亚铁氧化酶活性无法检测到，而使用 Western 膜分析检测到了显著的活性。免疫印迹方案检测到 CuD 啮齿动物血浆中 Cp 蛋白的主要减少（60-90%），但 qRT-PCR 检测到肝 mRNA 水平没有改变。数据与脱辅基 Cp 比全辅基 Cp 更不稳定一致。需要进一步研究来解释 CuD 小鼠中正常的血浆铁。Cp 的减少是铜缺乏的敏感生物标志物。
