Patent ID: 7553617

Claim:
A method for identifying a polynucleotide sequence that encodes a peptide which binds to a preselected receptor molecule, comprising: (1) transforming host cells by electroporation with at least 10 8 different filamentous bacteriophage expression vectors, wherein each of said different vectors comprises a polynucleotide sequence that encodes a fusion protein comprising a peptide fused to a pill coat protein of a filamentous bacteriophage so that the N-terminal amino acid of said fusion protein is the N-terminal amino acid of said peptide, and wherein said different vectors are constructed by ligating each polynucleotide of a mixture of at least 10 8 different polynucleotides to a bacteriophage cloning vector that encodes the coat protein so as to form a coding sequence for said fusion protein, wherein each of said different polynucleotides comprises a series of codons encoding a random collection of amino acids and encodes a different peptide; (2) cultivating the transformed cell under conditions suitable for expression and assembly of bacteriophage particles thereby displaying said peptides on the surface of said particles; (3) selecting bacteriophage particles displaying the peptide by combining said particles with the preselected receptor molecule and separating particles bound to said receptor molecule from unbound particles; and (4) sequencing said polynucleotide sequence encoding said peptide within said selected bacteriophage particles.