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>>/118770/ Directed evolution - a method used in protein engineering that mimics the process of natural selection to steer proteins or nucleic acids toward a user-defined goal Directed evolution (DE) is a method used in protein engineering that mimics the process of natural selection to steer proteins or nucleic acids toward a user-defined goal.[1] It consists of subjecting a gene to iterative rounds of mutagenesis (creating a library of variants), selection (expressing those variants and isolating members with the desired function) and amplification (generating a template for the next round). It can be performed in vivo (in living organisms), or in vitro (in cells or free in solution). Directed evolution is used both for protein engineering as an alternative to rationally designing modified proteins, as well as for experimental evolution studies of fundamental evolutionary principles in a controlled, laboratory environment. [insert] An example of directed evolution with comparison to natural evolution. The inner cycle indicates the 3 stages of the directed evolution cycle with the natural process being mimicked in brackets. The outer circle demonstrates steps in a typical experiment. The red symbols indicate functional variants, the pale symbols indicate variants with reduced function. History Directed evolution has its origins in the 1960s[2] with the evolution of RNA molecules in the "Spiegelman's Monster" experiment.[3] The concept was extended to protein evolution via evolution of bacteria under selection pressures that favoured the evolution of a single gene in its genome.[4] Lutz S (December 2010). "Beyond directed evolution--semi-rational protein engineering and design". Current Opinion in Biotechnology. 21 (6): 734–43. doi:10.1016/j.copbio.2010.08.011. PMC 2982887. PMID 20869867. Cobb RE, Chao R, Zhao H (May 2013). "Directed Evolution: Past, Present and Future". AIChE Journal. 59 (5): 1432–1440. doi:10.1002/aic.13995. PMC 4344831. PMID 25733775. Mills DR, Peterson RL, Spiegelman S (July 1967). "An extracellular Darwinian experiment with a self-duplicating nucleic acid molecule". Proceedings of the National Academy of Sciences of the United States of America. 58 (1): 217–24. Bibcode:1967PNAS...58..217M. doi:10.1073/pnas.58.1.217. PMC 335620. PMID 5231602. Hall BG (July 1978). "Experimental evolution of a new enzymatic function. II. Evolution of multiple functions for ebg enzyme in E. coli". Genetics. 89 (3): 453–65. doi:10.1093/genetics/89.3.453. PMC 1213848. PMID 97169. https://en.wikipedia.org/wiki/Directed_evolution