Amino-terminal sequence of a large form of basic fibroblast growth factor isolated from human benign prostatic hyperplastic tissue

Homogenization of human benign prostatic hyperplastic tissue in high ionic strength alkaline buffer containing protease inhibitors resulted in the isolation of a 17,400 molecular weight growth factor. When tissue was homogenized in ammonium sulfate at pH 4.5 without protease inhibitors a smaller, 16,600 dalton, growth factor was isolated. Both growth factors reacted with antisera against synthetic peptides whose sequences corresponded to the amino-terminal (1–12), Internal (33–43) and carboxyl-terminal (135–145) portions of basic fibroblast growth factor (bFGF). This suggested that the smaller growth factor was not a truncated form of (1–146) bFGF and that the larger growth factor may contain additional sequences. Amino-terminal sequencing showed the larger growth factor to have the sequence: Ala-Ala-Gly-Ser-Ile-Thr-Thr-Leu-Pro-Ala-Leu-Pro-Glu-Asp-Gly-Gly-Ser-Gly-Ala-Phe-Pro-. These results show that the larger growth factor is an 8 amino acid extended from of (1–146) bFGF and it is likely that the smaller growth factor is a proteolytic cleavage product of the larger growth factor produced during the extraction procedure.