Purification and characterization of hepatocyte growth factor (HGF) from human seminal plasma

Naturally occurring forms of hepatocyte growth factor/scatter factor (HGF/SF) have been purified by heparin-Sepharose chromatography, followed by cation exchange chromatography from a pool of human seminal plasma. Using an enzyme-linked immunosorbant assay, MDCK scatter assay, and Western blot analysis, it was found that, after heparin-Sepharose chromatography, human HGF/SF present in seminal plasma eluted in two different fractions, between 0.72 and 0.85 M NaCl (fraction I) and between 0.95 and 1.10 M NaCl (fraction II). Further purification of fraction I by cation exchange chromatography resulted again in two fractions which eluted at 0.2-0.4 and at 0.6-0.8 M NaCl. The fraction which eluted at 0.2-0.4 M NaCl consisted of two biologically less active heavy chains of the heterodimeric form of HGF/SF (107.1 U/ng immunoreactive HGF), with approximate molecular weights of 65 and 62 kDa under reducing conditions. The second fraction, which eluted at 0.6-0.8 M NaCl, revealed three bands with molecular weights of 87, 65 and 62 kDa, respectively. The 87 kDa form is thought to be a single chain precursor of HGF/SF devoid of biological activity. After subjecting fraction II to cation exchange chromatography, only one major peak eluted between 0.9 and 1.0 M NaCl, and consisted of two biologically active heavy chains of the heterodimeric form of HGF/SF (708.3 U/ng immunoreactive HGF), with approximate molecular weights of 65 and 62 kDa under reducing conditions. Nonreducing conditions for both fraction I and fraction II revealed only one band with a molecular weight of 68 kDa. The ratio ofpro-HGF/SF and less biologically active HGF/ SF (fraction I) over mature heterodimeric HGF/SF (fraction II) was approximately 1:3, in seminal plasma from sperm donors. In seminal plasma, pro-HGF/SF represents an 87 kDa glycoprotein which, apparently, is converted by limited proteolysis into several bands with molecular weights of 65 and 62 kDa. This is the first report showing the presence of pro-HGF/SF and heterodimeric mature HGF/SF, as well as less biologically active forms of HGF/SF in human seminal plasma.