Purification of heparin-binding protein HBp17 and identification of HBp17 heparin binding site

HBp17 was purified by Heparin-Copper biaffinity chromatography and HPLC from conditioned medium of A431 cell. The purified HBp17 was digested by staphylococcus urcus V8 protease or chymotrypsin and the heparin-binding fragments were isolated by Heparin-Sepharose. One binding site of peptide mapping is HBp17 residues 110-145 produced by V8. Another one is HBp17 residues 82-143 which were produced by chymotrypsin digestion. Two binding sites of peptide mapping are overlap. Therefore the residues 110-143 of HBp17 are the principle heparin binding site. The basic amino acid cluster in this region may be contribute to the binding of HBp17 to heparin or heparan sulfate proteoglycan on the cell surface and extracellular matrix.