Phage‐Displayed Combinatorial Peptides

Abstract

Phage-display is a convenient vehicle for the generation and screening of combinatorial peptide libraries for a variety of purposes. With standard molecular biology techniques, it is now possible to generate phage libraries displaying 10 10 different peptides, and screen them for peptide ligands to cell surfaces, metals, and proteins, or substrates of proteases, on the time frame of weeks.The first reported display of an exogenous protein fragment on the surface of bacteriophage occurred in 1985 [1]. In pioneering work by Professor George Smith, a fragment of the b-galactosidase protein of Escherichia coli was inserted into a gene encoding a minor capsid protein of M13 bacteriophage and the resulting phage were still infectious. Not only did the resulting chimeric phage particles display epitopes of the b-galactosidase protein, but also the fusion phage could be enriched more than 1000-fold over nonrecombinant phage with antibodies to the b-galactosidase protein.Protocols were subsequently developed that permitted a single fusion phage to be isolated, through affinity selection with antibodies, from an excess of 10 8 nonrecombinant phage particles [2].Combinatorial peptide libraries that were phage-displayed appeared in three simultaneous publications in 1990. In two of the publications, the linear epitopes of two different monoclonal antibodies were mapped by affinity selecting families of related peptides from libraries of 10 8 different peptides [3,4]. In the third publication, peptide ligands to streptavidin were selected from a library of 10 8 different peptides [5]. These three publications were unique in that libraries of such a large size were available for the first time and were sufficiently large enough to represent nearly all 6-mer peptide permutations. In addition, these combinatorial peptide libraries were proposed to be the source of peptide ligands to receptors, and thus serve as agonists and antagonists. Since then, phage-displayed combinatorial peptides have been the source of peptides that selectively bind cell and tissue surfaces [6-11], cytosolic proteins [12][13][14], receptors [15][16][17][18][19][20][21], inert materials [22,23], metals [24], and toxins [25][26][27].