Method of using a peptide library

Abstract

The present invention provides a peptide selected from the following (i) and (ii): (i) a peptide having the amino acid sequence represented by SEQ ID NO: 1 in the Sequence Listing; and (ii) a peptide having an amino acid sequence derived from the amino acid sequence represented by SEQ ID NO: 1 in the Sequence Listing by the conservative amino acid substitution, deletion, addition, or insertion of 1 to 28 (inclusive) amino acids except at the 1st Xaa to the 11th Xaa counting from the amino terminus.

1 . A method for identifying a peptide or peptide derivative that binds to a target molecule, comprising the following steps:
 (i) contacting peptides or peptide derivatives contained in a peptide library with the target molecule, wherein said peptide library comprises a plurality of peptides or peptide derivatives, wherein each peptide or peptide derivative has the amino acid sequence represented by SEQ ID NO: 1, wherein each amino acid at the 1st Xaa to the 11th Xaa of SEQ ID NO: 1 counting from the amino terminus is one of the following amino acids in approximately equal frequencies within the library: Ala, Glu, Gln, Asp, Asn, His, Trp, Arg, Lys, Val, Leu, Ile, Phe, Tyr, Ser, Met, Gly, and Thr, but is not cysteine or proline, and wherein the peptide library comprises at least one peptide selected from the group consisting of: (a) a peptide which binds to EphA2 (ephrin type-A receptor 2) and has the sequence of SEQ ID NO: 2, 3, or 4; (b) a peptide which binds to EGFR-Fc (epidermal growth factor receptor—Fc receptor) and has the sequence of SEQ ID NO: 5, 6, or 7;   (c) a peptide which binds VEGF (vascular endothelial growth factor) and has the sequence of SEQ ID NO: 8, 9, 10, 11, 12, or 13; and (d) a peptide which binds TNF-a (tumor necrosis factor alpha) and has the sequence of SEQ ID NO: 14, 15, or 16 ; and   (ii) recovering a peptide or peptide derivative binding to the target molecule.   
     
     
         2 . The method of  claim 1 , wherein the peptide library is a phage display library, a ribosome display library, or a nucleic acid display library. 
     
     
         3 . The method of  claim 1 , wherein the peptides or peptide derivatives are immobilized on a carrier. 
     
     
         4 . The method of  claim 1 , wherein the peptides or peptide derivatives are expressed on the surface of a eukaryotic or prokaryotic cell, viral particle, virus-like particle, phage, or phagemid. 
     
     
         5 . The method of  claim 1 , wherein the target molecule is an endogenous substance presented in a human or non-human animal individual or is an exogenous substance. 
     
     
         6 . The method of  claim 1 , wherein the target molecule is an endogenous or exogenous enzyme, receptor, receptor ligand, humoral factor, cytokine, biopolymer, cell, pathogen, toxin, and a substance derived therefrom. 
     
     
         7 . The method of  claim 6 , wherein the substance derived therefrom is a fragment, decomposition product, metabolite, or processed product which can be involved in directly or indirectly in the onset or exacerbation of a disease. 
     
     
         8 . The method of  claim 1 , wherein the target molecule is a molecule other than the endogenous ligands of TACI. 
     
     
         9 . The method of  claim 1 , wherein the target molecule is a non-natural substance. 
     
     
         10 . The method of  claim 9 , wherein the non-natural substance is a mineral, polymer, plastic, or synthetic low-molecular weight compound. 
     
     
         11 . The method of  claim 1 , wherein the target molecule is solid-phase immobilized. 
     
     
         12 . The method of  claim 1 , wherein the target molecule is isolated and/or purified from a tissue or cell. 
     
     
         13 . The method of  claim 1 , wherein the target molecule is synthesized. 
     
     
         14 . The method of  claim 13 , wherein the target molecule is a polypeptide prepared by in vitro translation. 
     
     
         15 . The method of  claim 1 , wherein the target molecule is a polypeptide prepared by expressing the polypeptide in a host cell comprising an expressing vector encoding same and purifying said polypeptide from the cell. 
     
     
         16 . The method of  claim 13 , wherein the polypeptide comprises a purification moiety. 
     
     
         17 . The method of  claim 16 , wherein the purification moiety is a histidine tag. 
     
     
         18 . The method of  claim 1 , wherein the contacting step comprises bringing the target molecule and the peptides or peptide derivatives of the peptide library into proximity such that they may interact with one another. 
     
     
         19 . The method of  claim 1 , wherein a peptide or peptide derivative of the library binds to the target molecule if the dissociation constant is less than 100 μM. 
     
     
         20 . The method of  claim 1 , wherein the method comprises solid-phase panning or liquid-phase panning.