Abstract
Heparin‐binding EGF‐like growth factor (HB‐EGF), which belongs to the EGF‐family of growth factors, was isolated from the conditioned medium of macrophage‐like cells. To investigate the effect of N‐ and C‐terminal residues of the EGF‐like domain of HB‐EGF in the binding affinity to the EGF receptor on A431 cell. We synthesized HB‐EGF(44–86) corresponding to the EGF‐like domain of HB‐EGF and its N‐ or C‐terminal truncated peptides. Thermolytic digestion demonstrated three disulfide bond pairings of the EGF‐like domain in HB‐EGF is consistent with that of human‐EGF and human‐TGF‐α. HB‐EGF(44–86) showed high binding affinity to EGF‐receptor, like human‐EGF. The truncation of the C‐terminal Leu^86^ residue from HB‐EGF(44–86), HB‐EGF(45–86) or HB‐EGF(46–86) caused a drastic reduction in the binding affinity to the EGF receptor. These results suggest that the EGF‐like domain of HB‐EGF plays an important role in the binding to the EGF receptor, and its C‐terminal Leu^86^ residue is necessary for binding with the EGF‐receptor. In addition, the deletion of the two N‐terminal residues (Asp^44^‐Pro^45^) from HB‐EGF(44–86) caused a 10‐fold decrease in relative binding affinity to the EGF receptor. This indicates that the two N‐terminal residues of the EGF‐like domain of HB‐EGF are necessary for its optimal binding affinity to the EGF receptor. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.