Chemical characterization of the two forms of epidermal growth factor in murine saliva

Extracts of murine salivary glands contain two molecular forms of epidermal growth factor, EGF I and EGF II (Petrides, P.E., Levine, A.E., Shooter, E.M. in: Peptides: - Synthesis, Structure and Function (Rich, D.H., Gross, E.eds.) p. 781 (1981]. We have identified both molecules not only in salivary gland extracts but also in saliva using only reverse phase liquid chromatography methodology. EGF I and II were isolated from submaxillary gland extracts in a ratio of 3:1 regardless of whether the classical isolation procedure or our rapid RPLC based technique was used. Both molecular forms were present in the same ratio in saliva of mice of both sexes when salivation was induced by epinephrine treatment of the animals. As judged by amino acid analysis and N-terminal sequencing salivary EGF I corresponds to the 53 amino acid sequence of murine EGF and EGF II is Des-ASN-EGF. The observation that EGF and Des-ASN-EGF are consecreted into saliva upon epinephrine stimulation implies a physiological role of EGF II which may be related to the high molecular weight EGF-complex.