PURIFICATION FROM HUMAN PLASMA OF A HEXAPEPTIDE THAT POTENTIATES THE SULFATION AND MITOGENIC ACTIVITIES OF INSULIN-LIKE GROWTH-FACTORS

The human plasma contains small peptide molecules known as low molecul ar weight growth factors synergistically increasing certain biological actions of insulin-like growth factors. In the present work. we isola ted and characterized a hexapeptide with HWESAS as structure. This pur ified peptide was absolutely necessary for the sulfation activity of i nsulin-like growth factor-I on chick embryo pelvic cartilages and impr oved the mitogenic activity of both insulin-like growth factors. The e ffects of this hexapeptide were confirmed by using the homologous synt hetic peptide, that exhibited similar biological effects. Other synthe tic peptides with structure derived from hexapeptide were shown to be active: the pentapeptide HWESA appeared more potent than the tripeptid e HWE, which is about 170 to 200 times less active than the hexapeptid e. The sequence of hexapeptide HWESAS is identified in only one human protein that is C3f, a fragment of C3 complement. (C) 1998 Academic Pr ess.