An affinity label for the anion binding site in ovotransferrin. Implications for iron release to reticulocytes

Bromopyruvate has been found to be an affinity label for the anion binding site in ovotransferrin. Spectral and radioactive labeling studies indicate that the bromopyruvate first forms a reversible ternary complex with ovotransferrin and iron and then reacts to yield the covalently bound product. This derivative is partially resistant to iron loss by protonation and suggests that protonation and loss of anion is a requisite first step for iron release to reticulocytes.