A (r)evolution in chemistry

  The power of evolution is revealed through the diversity of life. The Nobel Prize in Chemistry 2018 is awarded to Frances H. Arnold, George P. Smith and Sir Gregory P. Winter for the way they have taken control of evolution and used it for the greatest benefit to humankind. Enzymes developed through directed evolution are now used to produce biofuels and pharmaceuticals, among other things. Antibodies evolved using a method called phage display can combat autoimmune diseases and, in some cases, cure metastatic cancer.
(...)
  This process has now come so far that it has given rise to three individuals so complex they have managed to master evolution themselves. The Nobel Prize in Chemistry 2018 is awarded to Frances H. Arnold, George P. Smith and Sir Gregory P. Winter, because they have revolutionized both chemistry and the development of new pharmaceuticals through directed evolution. Let’s begin with the star of enzyme engineering: Frances Arnold.  
(...)
  For several years, she had tried to change an enzyme called subtilisin so that rather than catalysing chemical reactions in a water-based solution, it would work in an organic solvent, dimethylformamide (DMF). Now she created random changes – mutations – in the enzyme’s genetic code and then introduced these mutated genes into bacteria that produced thousands of different variants of subtilisin.

  After this, the challenge was to find out which of all these variants worked best in the organic solvent. In evolution, we talk about survival of the fittest; in directed evolution this stage is called selection.
 
  Frances Arnold utilised the fact that subtilisin breaks down milk protein, casein. She then selected the variant of subtilisin that was most effective in breaking down casein in a solution with 35 per cent DMF. She subsequently introduced a new round of random mutations in this subtilisin, which yielded a variant that worked even better in DMF.

  In the third generation of subtilisin she found a variant that worked 256 times better in DMF than the original enzyme. This variant of the enzyme had a combination of ten different mutations, the benefits of which no one could have worked out in advance.

  With this, Frances Arnold demonstrated the power of allowing chance and directed selection, instead of solely human rationality, to govern the development of new enzymes. This was the first and most decisive step towards the revolution we are now witnessing.

  The next important step was taken by Willem P. C. Stemmer, a Dutch researcher and entrepreneur who died in 2013. He introduced yet another dimension to the directed evolution of enzymes: mating in a test tube.

(continued at https://www.nobelprize.org/uploads/2018/10/popular-chemistryprize2018.pdf)