Puzzling Peptides from a Phage Display Library

Abstract

The commercial availability of random peptide libraries displayed on the M13 phage is increasing their use for<br />studies on epitope identification, enzyme inhibitors, receptor ligands, etc. In this study two experiments<br />where planned for selection of peptides. First with sheep antibodies, the positive selector was IgG, prepared<br />on Protein G column from a pool of 11 sheeps immunized, with a vaccine prepared from larvae of<br />Lucilia cuprina, against blowfly strike. The negative selector was IgG from the same sheeps before vaccination<br />and IgG from vaccinated non-immunized sheeps. Four rounds of positive and negative selections<br />with IgG from sheep were done respectively. In the second experiment using human IgG prepared on<br />a fresh Protein G column, again four rounds of positive selection with either IgG from MS and schizophrenia<br />patients were performed. This assay was alternated with two negative selections of schizophrenia IgG on<br />MS-associated peptides and vice versa and two negative selections on each with a control IgG. After the<br />fourth negative selection in each experiment, the phage was amplified and random clones were picked<br />for nucleotide sequencing. A total of 44 peptides were sorted with the PILEUP program and there was a large<br />number of 12-mer peptides containing either 4 or 5 methionine residues.<br /><br />