Nilsen T, Romslo I
Biochim Biophys Acta. 1985 Oct 17;842(2-3):162-9. doi: 10.1016/0304-4165(85)90198-9.
Isolated rat liver mitochondria accumulate iron from fully saturated transferrin at neutral pH. With 5 microM iron as diferric transferrin, accumulation at 30 degrees C amounts to approx. 40 pmol/mg protein per h. With access to a suitable porphyrin substrate, 70-80% of the amount of iron accumulated is recovered in heme. Mobilization of iron and synthesis of heme both depend on a functioning respiratory chain. Vacant iron-binding sites on mono- and apotransferrin compete with the mitochondria for iron mobilized from transferrin. Pyrophosphate at concentrations in the range 10-50 microM enhances mobilization of iron, counterbalances the inhibitory effect of mono- and apotransferrin and enhances metallochelatase activity. The results emphasize the putative suitability of pyrophosphate as an intracellular iron-transport ligand in situ.
分离的大鼠肝线粒体在中性pH条件下可从完全饱和的转铁蛋白中积累铁。以5微摩尔铁作为双铁转铁蛋白，在30℃时积累量约为每小时40皮摩尔/毫克蛋白质。若有合适的卟啉底物，积累的铁量中有70 - 80%可在血红素中回收。铁的动员和血红素的合成均依赖于功能正常的呼吸链。单转铁蛋白和脱铁转铁蛋白上的空铁结合位点与线粒体竞争从转铁蛋白中动员的铁。浓度在10 - 50微摩尔范围内的焦磷酸可增强铁的动员，抵消单转铁蛋白和脱铁转铁蛋白的抑制作用并增强金属螯合酶活性。这些结果强调了焦磷酸作为细胞内原位铁转运配体的假定适用性。
