Beta-epidermal growth factor is the des-asparaginyl form of the polypeptide

Reversed-phase high performance liquid chromatography of mouse epidermal growth factor (EGF) yielded two major forms, alpha- and beta-EGF, and a minor component, gamma-EGF. All three forms exhibited receptor-binding activity. Analysis of native alpha- and beta-EGF by mass spectrometry and partial Edman degradation led us to propose that alpha-EGF has a primary structure equivalent to that originally reported for EGF and that beta-EGF is the des-asparaginyl form of the polypeptide. When the purified alpha- and beta-polypeptides were cultured with human embryonic palatal mesenchymal cells stimulation of cell proliferation was observed at concentrations as low as 0.01 ng/ml with maximal stimulation occurring at about 1 ng/ml. Essentially no difference was noted in the mitogenic potency of the two forms. This suggests that the NH2-terminal region of EGF is not critical for mitogenic activity.