Effects of oxidation on mice epidermal growth factor

EGF contains a methionine residue at position 21. Oxidation of methionines in proteins has received some attention as a biochemical mechanism of ageing. In this study EGF was treated with oxidizing agents, i.e. chloramine T and H₂O₂, under conditions in which selective oxidation of methionine to methionine sulphoxide is known to occur in other biologically active polypeptides. Differences in the chromatographic behaviour of native and oxidized EGF were demonstrated using original reversed phase HPLC gradient systems. In spite of the differences in chromatographic behaviour, the biological activity of native and H₂O₂ treated EGF was the same. On the other hand, chloramine T treated EGF displayed a decreased biological activity, although the binding efficiency to the receptors was shown to be the same as that of native and H₂O₂ treated EGF.