Protein libraries

O Neil KT, Hoess RH, Jackson SA, Ramachandran NS, Mousa SA, DeGrado WF, Identification of novel peptide antagonists for GPIIb/Illa from a conformationally constrained phage peptide library, Proteins Structure, Function Genet., 14 509-515, 1992. 

Directed evolution bypasses the bottleneck of rational design and mimics natural evolution in a test tube to evolve proteins without knowledge of their structures. What fundamentally differentiates directed evolution from natural evolution is its power to significantly accelerate the process of evolution. As shown in Fig. 1, directed evolution uses various methods to generate a collection of random protein variants, called a library, at the DNA level. Followed by screening/selection of the library, protein variants with improvement in desired phenotypes are obtained. Usually, the occurrence of these functionally improved protein variants is a rare event thus, this two-step procedure has to be iterated several rounds until the goal is achieved or no further improvement is possible. 

A Kassarjian, V Schellemberger, CW Turck. Analysis of protein-protein interactions radiolabelled ligand screening of synthetic peptide libraries. Protein Sci 2 123 (391-T), 1993. 

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