Evolution is a powerful force that has shaped the history of every organism on this planet.
From the uniquely beaked finches from Darwin’s time to the pesticide-resistant insects of today, evolution is responsible for the great variety of life that we see on Earth.
Evolution depends on mutations – biological “mistakes”. Sometimes, these mistakes are helpful, and the organisms that have them live on to have offspring that inherit that “mistake”. Over time, nature favors that helpful trait. More and more members of the species are born with the helpful trait, and what started as a mistake becomes a norm.
It seems as if evolution is a purely biological concept, one that has no relation to chemistry. But it turns out that this is incorrect.
This year's Nobel Prize in Chemistry was shared between Frances Arnold of the California Institute of Technology, George Smith of the University of Missouri, and Gregory Winter of the MRC Laboratory of Molecular Biology in Cambridge, England. They showed how the basic principles of evolution could be used to create new enzymes and antibodies that are used to treat diseases..
Mutations - Not Mistakes!
The smallest unit of life is a cell. All cells hold code, or instructions for how to do their jobs. These instructions are stored in DNA.
The cell uses the DNA as a blueprint to create proteins that go on to perform a huge number of tasks. Some proteins form parts of the body, like hair or nails. Other proteins carry substances into or out of the cell, like tiny cellular vehicles. Still other proteins allow important chemical reactions to happen in the cell. No matter what task they’re performing, it’s clear that proteins are of paramount importance.
But sometimes, just like in nature, there are mistakes, or mutations. These mutations mean that when the cell makes the proteins, the proteins don’t come out quite right. They might be misshapen or they might not do their job correctly. But not all mistakes are problems. Sometimes mistakes can lead to improved proteins, proteins that do their job better and faster than the “correct” proteins.
When mutated proteins are helpful, their code (the DNA that was used to make them) gets passed on. These proteins go on to produce differently shaped beaks or fight pesticides inside insect bodies. Over time, the proteins evolve, and so do the organisms that they live inside.
This is why the laureates’ discoveries are so groundbreaking. They used evolution in a way that goes back to its roots – by taking the evolution we see in animals and applying it to the production of the proteins that caused it in the first place.
The Nobel Winning Work
Frances Arnold applied evolution to enzymes, which are proteins that perform extremely specific jobs. Scientists before Arnold attempted to create artificial enzymes on their own, but they had mixed results.
Arnold decided to attack the problem at its root. She induced mutations into cells, specifically into their DNA, causing the cells to produce different forms of the same enzyme. Once she found one particularly useful enzyme, she would repeat the process until she ended up creating an enzyme that did the exact job she wanted. Today, her work is used to produce renewable fuels, pharmaceuticals, and other proteins in a more environmentally friendly way.
George Smith and Gregory Winter used a similar technique to find proteins that could fight bacteria. Smith found viruses that could attack bacteria and disrupt their mechanisms. These viruses are called bacteriophages. Winter then took these same bacteriophages and engineered them so that they would create billions of antibodies that targeted different proteins. From these billions, Winter picked the ones that would target harmful proteins that cause disease.
This technique, called phage display, has been used to fight rheumatoid arthritis, psoriasis and inflammatory bowel diseases. It has also produced anti-bodies that can neutralize toxins, fight autoimmune diseases, and help cure metastatic cancer.
Sources: NPR, VOX, NobelPrize.org, NYTimes