Chemical synthesis and biological activity of the EGF‐like domain of heparin‐binding epidermal growth factor‐like growth factor (HB‐EGF)

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a recently discovered member of the epidermal growth factor (EGF) family. This novel growth factor possesses the EGF-like domain in the carboxyl portion. In order to evaluate the biological function of the EGF-like domain in HB-EGF, human HB-EGF(44-86) corresponding to the EGF-like domain was synthesized by the solid-phase procedure using the Fmoc strategy. It was confirmed by amino acid microsequencing of cysteine-containing fragments derived from thermolytic digestion that the pattern of three disulfide bond pairings in synthetic HB-EGF(44-86) was consistent with that of EGF and transforming growth factor-alpha (TGF-alpha). The homogeneity of the synthetic peptide was confirmed by analytical RP-HPLC, amino acid analysis and fast atom bombardment mass spectrometer (FAB-MS). Compared with h-EGF, the EGF-like domain of human HB-EGF showed a comparable mitogenic activity in the proliferation of NIH/3T3 fibroblast cells. These results suggest that the EGF-like domain of human HB-EGF may play an important role in mitogenic activity.