Apo-ovotransferrin

Human serum transferrin is an iron(m) tr ispoTt protein which gives up Fe + ions to bone marrow and placental tissues in preference to other cells such as liver cells the protein can bind two iron atoms per molecule but an anion such as HCOa" must be present for binding to occur. Vanadyl ion has been used (as an e.s.r. spin label) to show that the two metal-binding sites are non-equivalent and the same conclusion has been drawn from studies on the dissociation of labelled protein-bound iron. On the other hand, Harris and Aisen have obtained evidence from radiotracer experiments that the two sites are kinetically equivalent. The kinetics of iron(in) (in the form of ferric citrate) binding to the analogous apoprotein from hen s egg (apo-ovotransferrin) have been reported and the following minimum mechanistic scheme has been proposed ... 

FIG. 13 Calorimetric curves showing the heat denaturation of ovotransferrin (conalbu-min) in solution, (a) Apo-ovotransferrin (b, c) ovotransferrin 39% saturated with iron (d) ovotransferrin fully saturated with iron. The bar represents a heat flow of 500 (iJ/s. Instrument DuPont thermal analyzer 990. (From Ref. 85.)... 

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