Selective reduction of a disulphide bridge in hen ovotransferrin

Brief treatment of iron-saturated hen ovotransferrin with dithiothreitol selectively cleaves the disulphide bridge between residues 478 and 671, which is in the C-terminal domain of the protein. The reduced alkylated protein is less stable than the native protein, and its iron-binding properties are different. A fluorescent derivative was prepared by coupling N-iodoacetyl-N'-(5-sulpho-1-naphthyl)ethylenediamine to the thiol groups.