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I never thought I would end up in a school like Caltech pursing a PhD in chemical engineering. When I was young, I wanted to become a medical doctor so that I could help people. It wasn’t until my last year of high school, when I started seriously considering my career path, that I realized all of the people I most wanted to be like were engineers. This realization spurred my decision to go into engineering, because I believed it would best allow me to solve complex problems and contribute to society in a meaningful way.

I have been at Caltech for just over a year now, and while it has been one of the most challenging experiences of my life, I am exceedingly grateful and excited to be here.

I work for the renowned scientist Dr Frances Arnold, who is a judge for the Queen Elizabeth Prize for Engineering. In the Arnold lab, we focus on engineering new biocatalysts, which are proteins that allow chemical reactions to proceed more easily.  We engineer these biocatalysts using a process called ‘directed evolution.’

Directed evolution involves engineering proteins by manipulating their DNA. The resulting enzymes are then tested to see if they can complete the desired reaction faster and more efficiently than before. Those found to have increased activity then go through further rounds of DNA manipulation. The end goal of the process is to create a final protein with very high reactivity.

Every biological process imaginable uses highly specialized molecules; from plants converting sunlight into sugar, to your body transmitting touch sensations from your finger to your brain. This means that medicines that interact with the biological reactions in our bodies must have very specific structures.

Traditional methods used to make medicines with these structures often require harsh solvents and conditions. Biocatalysts can make them in water instead, under mild conditions. Until recently, biocatalysts have not been widely used in the synthesis of chemicals, because of the limited number of reactions they could speed up. In our lab, we use directed evolution to expand the scope of reactions and substances on which enzymes can act.

The work I have been doing in the lab has focused on using this powerful process to make precursors to pharmaceutical medications. These are the initial chemicals from which pharmaceutical drugs are made. I recently published a study that explored engineering a protein called a globin. This particular protein was engineered to speed up the formation of a molecule used in making a medication that prevents heart attacks.

Frances Arnold is an exceedingly accomplished and brilliant engineer, and working for her has given rise to so many opportunities for me that I never thought I would have. Through my work at Caltech I am contributing to engineering research in a real and tangible way, and I believe the innovations the Arnold lab is developing will improve life for us all. During the remainder of my time here, I will continue to work on biocatalysts to help provide more environmentally friendly methods for chemical synthesis.

Kari Hernandez

Kari Hernandez

Kari Hernandez is a Ph.D. candidate in chemical engineering at Caltech. She is a member of the Arnold lab working on the development of engineered enzymes to act as green catalysts in the production of chemicals. She obtained her B.S. in chemical engineering from the University of Arizona.
Kari Hernandez

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