Peptides for use in culture media

Abstract

The present invention provides peptides libraries which are useful for rapid identification of biologically active compounds. The invention further provides peptides which include cell-growth affecting peptides and peptides which enhance or inhibit production of cellular proteins. Many of the peptides of the invention may be produced in large quantity by recombinant techniques and formulated in culture medium to produce the desired effect on cultured cells and tissues. Certain of the libraries of the invention and the peptides identified in them are particularly useful in concatemer-based recombinant expression methods.

1 . A method for identifying a biologically active peptide having a desired biological activity, comprising: 
 (a) constructing a peptide library of chemically synthesized peptides, each of the peptides comprising: 
 (i) an N-terminal or C-terminal amino acid associated with enzymatic or chemical cleavage of a polypeptide; and  
 (ii) one or more additional amino acids; and  
   (b) screening the peptide library for biological activity.    
     
     
         2 . The method of  claim 1 , wherein the biological activity comprises enhancing or inhibiting cell growth.  
     
     
         3 . The method of  claim 2 , wherein growth of  C. perfringens  is enhanced or inhibited.  
     
     
         4 . The method of  claim 1 , wherein the biological activity comprises enhancing or inhibiting cellular protein production.  
     
     
         5 . The method of  claim 4 , wherein enhancing or inhibiting cellular protein production comprises enhancing or inhibiting toxin production.  
     
     
         6 . The method of  claim 5 , wherein production of β-toxin is enhanced or inhibited.  
     
     
         7 . The method of  claim 1 , wherein said N-terminal amino acid of the peptides is selected from the group consisting of alanine, aspartic acid, glycine, isoleucine, leucine, methionine, phenylalanine, proline, serine, tyrosine, tryptophan, and valine.  
     
     
         8 . The method of  claim 1 , wherein said C-terminal amino acid of the peptides is selected from the group consisting of arginine, asparagine, aspartic acid, glutamic acid, leucine, lysine, methionine, phenylalanine, proline, tryptophan, and tyrosine.  
     
     
         9 . The method of  claim 1 , wherein said peptide library is a tetrapeptide library.  
     
     
         10 . The method of  claim 9 , wherein each of the tetrapeptides comprise a sequence of XXAL, where X represents glutamic acid, glutamine, serine, alanine, valine, leucine, phenylalanine, lysine, proline, or glycine, A represents alanine, and L represents leucine.  
     
     
         11 . The method of  claim 9 , wherein each of the tetrapeptides comprise a sequence of XXXL, where X represents glutamic acid, glutamine, serine, alanine, valine, leucine, phenylalanine, lysine, proline, or glycine and L represents leucine.  
     
     
         12 . The method of  claim 9 , wherein each of the tetrapeptides comprise a sequence of ZZAL, where Z represents glutamic acid, aspartic acid, glutamine, asparagine, serine, threonine, alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, tryptophan, lysine, arginine, proline, histidine, glycine, or cysteine, A represents alanine, and L represents leucine.  
     
     
         13 . The method of  claim 9 , wherein each of the tetrapeptides comprise a sequence of ZZZL, where Z represents glutamic acid, aspartic acid, glutamine, asparagine, serine, threonine, alanine, valine, isoleucine, leucine, methionine, phenylalanine, tyrosine, tryptophan, lysine, arginine, proline, histidine, glycine, or cysteine and L represents leucine.  
     
     
         14 . The method of  claim 1 , wherein said peptide library is a pentapeptide library.  
     
     
         15 . The method of  claim 1 , wherein said peptide library is a hexapeptide library.  
     
     
         16 . The method of  claim 1 , wherein screening the peptide library for biological activity comprises culturing cells or tissues in the presence of a peptide selected from the peptide library.  
     
     
         17 . The method of  claim 16 , wherein culturing cells or tissues in the presence of a peptide selected from the peptide library comprises culturing the cells or tissues in a chemically defined medium, a serum-free medium, or a hydrolysate-free medium.  
     
     
         18 . The method of  claim 16 , wherein the cells or tissues are cultured in the presence of about 0.1 mM to about 25 mM of the peptide.  
     
     
         19 . The method of  claim 18 , wherein the cells or tissues are cultured in the presence of about 1.0 mM to about 12 mM of the peptide.  
     
     
         20 . The method of  claim 1 , wherein the enzymatic or chemical cleavage of a polypeptide comprises cleavage with pepsin, papain, chymotrypsin, trypsin, cyanogen bromide, V8 protease, thermolysin, cathepsin G, endoproteinase Lys-C, endoproteinase Asp-N, proteinase K, or proline endopeptidase.  
     
     
         21 . A method for identifying a peptide that enhances or inhibits cell growth, comprising: 
 (a) constructing a peptide library of chemically synthesized peptides, each of the peptides comprising: 
 (i) an N-terminal or C-terminal amino acid associated with enzymatic or chemical cleavage of a polypeptide; and  
 (ii) one or more additional amino acids; and  
   (b) screening the library in a cell growth assay.    
     
     
         22 . The method of  claim 21 , wherein said N-terminal amino acid of the peptides is selected from the group consisting of alanine, aspartic acid, glycine, isoleucine, leucine, methionine, phenylalanine, proline, serine, tyrosine, tryptophan, and valine, and wherein said C-terminal amino acid of the peptides is selected from the group consisting of arginine, asparagine, aspartic acid, glutamic acid, leucine, lysine, methionine, phenylalanine, proline, tryptophan, and tyrosine.  
     
     
         23 . A method for identifying a peptide that enhances or inhibits cellular protein production, comprising: 
 (a) constructing a peptide library of chemically synthesized peptides, each of the peptides comprising: 
 (i) an N-terminal or C-terminal amino acid associated with enzymatic or chemical cleavage of a polypeptide; and  
 (ii) one or more additional amino acids; and  
   (b) screening the library in a cellular protein production assay.    
     
     
         24 . The method of  claim 23 , wherein said N-terminal amino acid of the peptides is selected from the group consisting of alanine, aspartic acid, glycine, isoleucine, leucine, methionine, phenylalanine, proline, serine, tyrosine, tryptophan, and valine, and wherein said C-terminal amino acid of the peptides is selected from the group consisting of arginine, asparagine, aspartic acid, glutamic acid, leucine, lysine, methionine, phenylalanine, proline, tryptophan, and tyrosine.  
     
     
         25 . The method of  claim 23 , wherein enhancing or inhibiting cellular protein production comprises enhancing or inhibiting toxin production.