Affinity purification of proteins using ligands derived from peptide libraries

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Abstract
Peptide libraries can be used to identify ligands that bind specifically to a desired protein. These peptides may have significant advantages as specific ligands for affinity chromatography separations. This article describes the use of one of such peptide, Try‐Asn‐Phe‐Glu‐Val‐Leu, as a ligand for the purification of S‐protein using affinity chromatography. General strategies for peptide immobilization are discussed and the conditions for peptide immobilization to Emphaze™ gel are optimized. The effects of peptide orientation and peptide densities on protein binding are studied. Results indicate that the peptide affinity is not affected by the orientation of the peptide during immobilization, but association constants can be reduced by one order of magnitude when compared with the values in solution.With increased peptide density, the protein binding capacity of the gel increases, but both the percentage of peptide utilization and apparent binding constant between immobilized peptide and S‐protein decrease. S‐protein is separated from a mixture with BSA via affinity chromatography using specific elution with the peptide in solution.Finally, direct purification of S‐protein from an enzymatic digestion mixture of ribonuclease A is demonstrated.© 1995 John Wiley & Sons, Inc