Phage screening peptide selection

In some cases, functional assays have been used to screen phage-display peptide libraries. For example, a phage-display hexapeptide library was constructed with an epitope tag distal (N-terminus) to screen for peptide substrates of a specific protease. All the phages were captured by an immobilized anti-epitope antibody. After incubation with a tissue plasminogen activator (tPA), phages that expressed a peptide substrate for tPA were released for subsequent rounds of selection. A similar approach was applied to discover peptide substrates for HIV-1 protease. 

A phage-displayed peptide library was screened to identify peptides that selectively bind to lung tumor cells. The synthetic CSNIDARAC peptide strongly bound to H460 cells and was efficiently internalized into the cells... 

Since its introduction, this technique has gained more and more importance in the combinatorial field. The main advantage of biological libraries, in comparison to chemical libraries, depends on the possibility of increasing remarkably the number of different molecules that can be screened at the same time. Furthermore, once the phage displaying the active sequence has been selected, it is able to replicate itself by infecting host bacterial cells successive selection and amplification cycles result in an exponential enrichment of the active peptide sequence. 

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