Enzymes are extremely complex molecules, consisting of as many as several thousand amino acids linked together in long chains, folded up into three-dimensional structures. Yet, with ingenuity, their architecture can be remodeled to give new properties that are useful to mankind. In the early 1990s, a young Frances Arnold (b. 1956), then at the California Institute of Technology, turned to nature for ideas on how to do this. There she succeeded in using emerging DNA technology to design new enzymes to produce pharmaceuticals, plastics and other chemicals that would otherwise be made with toxic materials.

Calling her method, “directed evolution”, Arnold would start by introducing mutations into the DNA of a particular protein, then reinsert the new variants into bacteria, which then produce new proteins. She then selects those proteins that exhibit the desired properties, extracts their DNA and repeats the process, breeding new generations of proteins that does exactly what she wants. It’s Darwin’s survival of the fittest at work, except that Arnold decides what “fittest” means. For her pioneering efforts, Arnold was awarded the 2018 Nobel Prize in Chemistry at the age of 62.

“Nature has explored only a tiny fraction of the life and life’s molecules that are possible. With evolution in our hands, with the ability to set genetic diversity and to tailor the forces of selection, we can now explore paths that Nature has left unexplored.”

~ Frances Arnold