Adhesive peptides selected by phage display: characterization, applications and similarities with fibrinogen

Phase clones with affinity for polystyrene/polyurethane magnetic particles were isolated from a 10-men peptide display library. Sequence analysis revealed that 40 out of 80 clones contained the consensus WXXWXXXW. Some of the selected phages showed high surface activity and adsorbed to plastic surfaces even in the presence of blocking agents or surfactants. Covalent attachment of a synthetic peptide (KG), carrying one of the selected sequences to alkaline phosphatase (AP) or bovine serum albumin (BSA) enhanced binding of AP to a wide range of materials and improved the ability of BSA to prevent binding of antibodies and phages to polystyrene. Interestingly, the WXXW/XXXW motif occurs in the beta- and gamma-chains of the natural "adhesive" protein fibrinogen, and a synthetic peptide carrying the gamma-chain 369-376 sequence turned out to have essentially the same binding properties as the KG peptide. Furthermore, adsorption in different types of polystyrene was similar for AP carrying either the KG or gamma-chain peptide intact fibrinogen and plasmin-generated fragment D1. The latter fragment contains two copies of the WXXWXXXW motif but lacks the alpha-chain: protuberances previously implicated in fibrinogen adsorption. Thus, our study may have revealed a hitherto unknown structural determinant for fibrinogen's adsorptivity, located in the 13-kDa C terminal region of the gamma-chain.