Professor Frances Arnold is a chemical engineer who managed to create proteins that literally change the way we can control our environment. We’re all aware of evolution and its principles (Hello, Darwin!) but in this case, she managed to use these principles to carry out the directed evolution of enzymes! Complicating? Let’s break it down. The work was done in conjunction with Prof. George P. Smith and Sir Gregory P. Winter which won them the Nobel in Chemistry in the year 2018.

What is directed evolution?

This is specifically a technique where bioengineers, such as Prof. Arnold use the natural process of evolution to engineer proteins that meet a previously user-defined goal. For example, do you want to engineer enzymes (proteins) that can break down oil, such that they can be used for oil spills? This is the technique you would use. It involves multiple rounds of mutagenesis, where mutations (changes in the gene) are induced and then, selected isolated once the desired mutation is achieved.

Schematic representation of directed evolution (outer circle) compared to natural evolution (the inner circle)
Schematic representation of directed evolution (outer circle) compared to natural evolution (the inner circle)

Dawn of discovery

After her postdoctoral work, she decided to use DNA technology to engineer enzymes that could be used in many industries to produce pharmaceuticals, etc. that would either be made using toxic chemicals that are extremely harmful to our environment and our own health as well. Now, this is where the challenge begins. Enzymes are already very complex molecules that involve many amino acids that would be difficult to engineer. So, how do you remodel these structures to give them a new and improved function for a completely different purpose than their original one? It’s almost impossible unless you look in a different direction!

This is where the idea to look at nature’s principles came into place and that’s when the team decided to look at evolution. Why not use an already existing principle to engineer these proteins instead? She experimented with subtilisin, an enzyme that is naturally produced by a bacterial species known as Bacillus subtilis, and induced mutations in them. After isolating and reinserting the mutated genes into bacteria, she bred one generation after the other until she got the desired protein. This completely changed the way we look at proteins and gave rise to an entire field of protein engineering!


Even though structural biologists at the time were confounded by the workings of such enzymes as they had no understanding of why this works. Now, we have come to a point where we can virtually create any type of protein we want and express it to protect our environment. It has been used to develop proteins that can breakdown oil during oil spills, used in the production of many pharmaceutical products that cure people, and even to produce renewable fuels, a technology that is much needed in today’s date.

Her work changed the way we view and use proteins in our daily life and has changed the field of science by allowing many scientists to engineer critically impactful products! She has also been a huge believer of encouraging women in science and believes that through such achievements, women would be reassured of the fact that they can also amount to doing great things in life.


Frances H. Arnold. (2018). Retrieved from

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