SELECTION OF PEPTIDES THAT BIND TO PLASMINOGEN-ACTIVATOR INHIBITOR-1 (PAI-1) USING RANDOM PEPTIDE PHAGE-DISPLAY LIBRARIES

Large random hexa- and decapenta-peptide libraries were constructed an d displayed on the surface of the filamentous phagemid pComb8. Fanning of the hexa-peptide library on immobilized plasminogen activator inhi bitor 1 (PAI-1) specifically selected a minor fraction of concatemers, indicating that binding to PAI-1 requires an extended amino acid sequ ence. Accordingly, the decapenta-peptide library exclusively yielded P AI-1 binding peptides of 15 amino acid residues. None of these phage-b ound peptides prevented the interaction between PAI-1 and its target s erine protease urokinase (u-PA), To isolate peptides that block the in teraction between PAI-1 and U-PA, phages bound to immobilized PAI-1 we re eluted by incubation with u-PA. Remarkably, this procedure resulted in elution of a unique phage type that harbors a concatemer of decape ntamers, consisting of 49 amino acid residues with no obvious similari ty to the primary sequence of PAI-1 or u-PA. (C) 1998 Federation of Eu ropean Biochemical Societies.