Scanning synthetic peptide combinatorial libraries: oligopeptide mixture sets having a one predetermined residue at a single, predetermined position, methods of making and using the same

A process for providing the amino acid residue sequence of an oligopeptide ligand that specifically binds to an acceptor that comprises the steps of:

• (a) providing a plurality of sets of self-solubilizing, unsupported mixed oligopeptides in which each set consists essentially of a mixture of equimolar amounts of linear oligopeptide chains containing the same number of five to ten amino acid residues in each oligopeptide chain, the members of each set having one of at least six predetermined amino acid residues at a single, predetermined position of the oligopeptide chain, and each set having equimolar amounts of the same at least six different amino acid residues at the same other positions of the oligopeptide chain, said plurality of sets having equimolar amounts of said at least six different amino acid residues at said other positions in the oligopeptide chain but differing in that said one of at least six predetermined amino acid residues present at the predetermined chain position within each set is different between the sets;
• (b) separately admixing each set from said plurality of sets with said acceptor in an aqueous medium at a concentration of about 0.1 milligrams per liter to about 100 grams per liter, separately assaying the binding of each set to said acceptor, and determining the one or more sets of the plurality of sets that provided specific binding compared to the other sets assayed;
• (c) providing another plurality of sets of self-solubilizing, unsupported mixed oligopeptides in which each set consists essentially of a mixture of equimolar amounts of linear oligopeptide chains containing the same number of five to ten amino acid residues in each oligopeptide chain and having the same chain length as the first named plurality of sets, the members of each set having one of at least six predetermined amino acid residues at another single, predetermined position of the oligopeptide chain different from said first-named sets, and each set having equimolar amounts of the same at least six different amino acid residues at the same other positions of the oligopeptide chain, said other plurality of sets having equimolar amounts of said at least six different amino acid residues at said other positions in the oligopeptide chain but differing from other set pluralities in that the one of at least six predetermined amino acid residue present at the predetermined chain position within each set is different between the set pluralities;
• (d) separately admixing each set from said other plurality of sets with said acceptor in an aqueous medium at a concentration of about 0.1 milligrams per liter to about 100 grams per liter, separately assaying the binding of each other set to said acceptor, and determining the one or more sets of the other plurality of sets that provided specific binding compared to the other sets assayed;
• and
• (e) repeating steps (c) and (d) using further pluralities of sets that differ from each other and the set pluralities of steps (a) and (c) by the chain position of the one of at least six predetermined amino acid residues at the predetermined chain position until at least five pluralities of sets have been assayed, the number of sets in each plurality of sets assayed being equal to the number of different amino acid residues present at the positions at which equimolar amounts are present;
• wherein the identity and position of the one of at least six amino acid residues of said each one or more sets that provided specific binding so determined for each plurality of sets provides the amino acid residue sequence for said ligand that specifically binds to said acceptor.

A process for providing a six amino acid residue sequence of an oligopeptide ligand that specifically binds to an acceptor that comprises the steps of:

• (a) providing six separate pluralities of sets of self-solubilizing, unsupported mixed oligopeptides, each of said pluralities having sets that consist essentially of a mixture of equimolar amounts of linear oligopeptide chains containing six amino acid residues in each chain, the members of each set having one of at least ten predetermined amino acid residues at a single, predetermined position of the oligopeptide chain, and having the same at least ten different amino acid residues at the same other positions of the oligopeptide chain, each set of a plurality of sets having equimolar amounts of at least ten different amino acid residues at said other positions in the oligopeptide chain but differing in that the one of the at least ten predetermined amino acid residues present at the predetermined chain position within each set is different between the sets, and each of the plurality of sets differing from the other pluralities of sets by the position of the one of at least ten predetermined amino acid residues in the oligopeptide chain;
• (b) separately admixing each set from a first plurality of sets with said acceptor in an aqueous medium at a concentration of about 1 milligram per liter to about 100 grams per liter, separately assaying the binding of each set to said acceptor and determining the one or more sets that provided specific binding for that plurality of sets;
• and
• (c) repeating step (b) using each of the remaining pluralities of sets in place of said first plurality of sets;
• wherein the identity and position of the amino acid residue of said each one or more sets that provided specific binding for each plurality of sets provides the six amino acid residue sequence for said ligand that specifically binds to said receptor.