A road trip to Florida is always memorable for kids, usually for the road snacks and sibling arguments rather than the highways they took to get there. But ask what cities and sketchy tourist traps they stopped at, and one might be able to reconstruct the route.
Squire Booker specializes in reconstructing routes from pins on the map, not along highways, but via chemical reactions.
“In chemistry, these pins represent what we call intermediates—the forms that molecules take along the way during a reaction’s various steps,” says Booker, a biochemist at Penn State. “Studying these intermediates gives us a better picture of how a reaction proceeds at each of its various steps. The more intermediates we identify, the better that picture is.”
Booker studies the intermediates of biological reactions that rely on a radical S-adenosylmethionine, or radical SAM, enzyme. Enzymes in this family are involved in a huge variety of chemical reactions within a cell, from the production of antibiotics, to modifying proteins after they are created, to catalyzing—speeding up—complex biological reactions. Disruption of radical SAM enzymes in humans can lead to a range of serious health problems including Type II diabetes, congenital heart disease, ALS, and increased susceptibility to viral infections.
Radical SAM enzymes are found in more than three thousand organisms, from humans to bacteria that live in oxygen-free environments, and are represented by more than 400,000 unique protein sequences. Researchers have documented over a hundred roles of radical SAM enzymes, but given the huge number of these enzymes that are still uncharacterized, that number is bound to increase.
“We don’t know what the majority of them do,” says Booker. “We have started to go through these enzymes to see what reactions they catalyze and how these reactions actually work.”