Preparation of soluble peptide libraries: application to studies of platelet adhesion sequences.

We describe chemical synthesis of peptide mixtures that equally express many sequence combinations. Using 65 couplings of single amino acids, five mixtures were prepared with the sequences Tyr-Gly-Arg-Gly-Yyy-Xxx-Xxx, where Yyy is Ser, Asp, Arg, Asn, or Glu, and Xxx is any amino acids. Compositional and sequence analyses supported full representation of all amino acids, except isoleucine was deficient in the sixth position. The data suggest formation of a repertoire of 1,900 sequence combinations (5 x 19 x 20). The mixture with Asp as the fifth residue inhibited platelet adhesion to fibronectin more effectively than the other mixtures. Peptide libraries offer a new tool for investigating bioactive peptides.