Human serum transferrin can bind up to two iron atoms, one in each of its two domains which are known as the N-lobe and the C-lobe. Ferric pyrophosphate and ferric citrate have been shown to direct loading into the C-lobe and N-lobe, respectively. We report that the iron supplement ferric pyrophosphate citrate directs iron to the C-lobe. We also show that pyrophosphate directs iron to the C-lobe as a free anion even at the concentrations found in human plasma. This indicates that pyrophosphate may play a physiological role in transferrin iron loading and body iron homeostasis. We also present a validation of an existing micellar capillary electrophoresis technique for separating the four transferrin metalloforms, which has potential to be adapted for use in a clinical setting.
Keywords: Ferric pyrophosphate citrate; Metalloforms; Micellar electrokinetic chromatography; Pyrophosphate; Synergistic anion; Transferrin.
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