With an air tank strapped to her back, college student Emily Scott dove to the bottom of the Gulf of Mexico to examine life in an oxygen-starved area called the Dead Zone. The bottom waters had once teemed with red snapper, croaker and shrimp, but to Scott, the region appeared virtually devoid of life. Then, from out of the mud, appeared the long, undulating arms of a brittle star.
As Scott learned, that particular species of brittle star survived in the Dead Zone because it has something many other marine creatures don’t: an oxygen-carrying protein called hemoglobin. This same protein makes our blood red. Key to hemoglobin’s special oxygen-related properties is a small molecular disk called a heme (pronounced HEEM).
Once she saw what it meant to brittle stars, Scott was hooked on heme and proteins that contain it.
Now an associate professor, Scott studies a family of heme proteins called cytochromes P450 (CYP450s). These proteins are enzymes that facilitate many important reactions: They break down cholesterol, help process vitamins and play an important role in flushing foreign chemicals out of our systems.
To better understand CYP450s, Scott uses a combination of two techniques–X-ray crystallography and nuclear magnetic resonance spectroscopy—for capturing the enzymes’ structural and reactive properties.
She hopes to apply her work to design drugs that block certain CYP450 reactions linked with cancer. One target reaction, carried out by CYP2A13, converts a substance in tobacco into two cancer-causing molecules. Another target reaction is carried out by CYP17A1, an enzyme that helps the body produce steroid sex hormones but that, later in life, can fuel the uncontrolled growth of prostate or breast cancer cells.
“I’m fascinated by these proteins and figuring out how they work,” Scott says. “It’s like trying to put together a puzzle—a very addictive puzzle.” Her drive to uncover the unknown and her willingness to apply new techniques have inspired the students in her lab to do the same.
Content adapted from “Hooked on Heme,” an article in the September 2013 issue of Findings magazine.