Explained: Directed evolution
In nature, evolution takes place over eons: A slow accumulation of adaptations gradually produces new traits and species. But evolution can also happen on a small and fast scale in the laboratory.The approach is called “directed evolution,” and scientists are using it to generate proteins that do not occur in nature — for example, cancer drugs, new microbial enzymes for converting agricultural waste to fuel, or imaging agents for magnetic resonance imaging (MRI).Most protein structures are so complex that it’s nearly impossible to predict how altering their structure will affect their function. So the trial-and-error approach of directed evolution is usually the fastest way to come up with a new protein with desirable traits, says Dane Wittrup, an MIT professor of chemical and biological engineering who uses directed evolution to discover new antibodies that target cancer cells.Such experiments often yield proteins that researchers never would have come up with on...