The use of high-performance liquid chromatography in the isolation and characterisation of mouse and rat epidermal growth factors and examination of apparent heterogeneity.

Various epidermal growth factor preparations obtained from the mouse submaxillary gland (mEGF), have been separated into a number of components by reversed-phase high-performance liquid chromatography (HPLC). It is shown here, however, that when the mEGF is isolated rapidly, using only reversed-phase HPLC for trace enrichment and high-resolution fractionation, it is a single molecular species as determined with several ion-pairing solvent systems, provided that proteolysis is inhibited in the original extracts. This indicates that the minor components of mEGF that have been reported are artefacts formed during the isolation procedure, and are of no biological significance. The products of deliberate mild degradation of mEGF are shown to produce similar chromatographic profiles to those observed in samples of mEGF prepared in the absence of proteolytic inhibitors. Rat EGF has been isolated in a similar manner, and is shown to share many of the properties of the major tryptic digestion product of mEGF.