Complete Amino Acid Sequence Determination of Rat Epidermal Growth Factor:Characterization of a Truncated Form with Full In Vitro Biological Activity

Epidermal growth factor (EGF), first isolated by Cohen(l) in 1962 from adult mouse submaxillary glands, is a single-chain polypeptide of 53 residues with three disulfide bonds(2,3). It is a potent stimulator of cellular proliferation (4,5) and inhibitor of gastric acid secretion(6). Although the chemical and biological properties of EGF have been studied extensively over the past 20 years (for reviews see 7–9) a detailed understanding of its three-dimensional structure is still not known. The lack of success with tertiary structure studies (e.g. X-ray crystallography NMR) may, in part, be attributable to the N-terminal heterogeneity encountered with many EGF preparations; this heterogeneity has been studied in detail for two forms of mouse EGF which differ by a lack of one N-terminal residue(10,11).