Morgan E H
Biochim Biophys Acta. 1977 Aug 25;499(1):169-77. doi: 10.1016/0304-4165(77)90239-2.
The ability of a large number of cellular metabolites to release iron from transferrin was investigated by measuring the rate at which they could mediate iron exchange between two types of transferrin. Rabbit transferrin labelled with 59Fe was incubated with human apotransferrin in the presence of the metabolites. After varying periods of incubation the human transferrin was separated from the rabbit transferrin by immunoprecipitation. GTP, 2,3-diphosphoglycerate, ATP, ADP and citrate produced the most rapid exchange of iron between the two types of transferrin, but many other compounds showed some degree of activity. Iron exchange mediated by the organic phosphates had the characteristics of a single first-order reaction and was sensitive to changes of incubation temperature and pH. The activation energy for the exchange reaction was approx. 13 kcal/mol. The rate of iron exchange from the oxalate - iron - transferrin complex was much lower than from bicarbonate - iron - transferrin. It is concluded that several organic phosphates have the capacity of releasing iron from transferrin. These compounds may represent the means by which the iron is released during the process of cellular uptake.
通过测量大量细胞代谢产物介导两种转铁蛋白之间铁交换的速率，研究了它们从转铁蛋白释放铁的能力。将用59Fe标记的兔转铁蛋白与脱铁转铁蛋白在代谢产物存在的情况下一起孵育。经过不同的孵育时间后，通过免疫沉淀将人转铁蛋白与兔转铁蛋白分离。GTP、2,3-二磷酸甘油酸、ATP、ADP和柠檬酸盐在两种转铁蛋白之间产生了最快速的铁交换，但许多其他化合物也表现出一定程度的活性。有机磷酸盐介导的铁交换具有单一一级反应的特征，并且对孵育温度和pH的变化敏感。交换反应的活化能约为13千卡/摩尔。草酸盐-铁-转铁蛋白复合物中铁的交换速率远低于碳酸氢盐-铁-转铁蛋白。得出的结论是，几种有机磷酸盐具有从转铁蛋白释放铁的能力。这些化合物可能代表了细胞摄取过程中铁释放的方式。
