By Lauren Mar ’25
From Aaron Leconte’s lab at the W.M. Keck Science Department to the University of Illinois at Urbana-Champaign, Susanna Barrett ’19 continues to carry her college experience with her throughout graduate school.
Barrett is currently a graduate student researcher in chemistry, and pursuing a PhD, but when she first joined Leconte’s lab in her sophomore year, she was questioning whether she wanted to do research in the future.
“Aaron’s lab was critical to my development as a scientist,” says Barrett, who majored in biochemistry. “Not only was he a great mentor, I also had smart, thoughtful Scripps students going to grad school as my role models. I did full-time research the summer between my sophomore and junior year, which helped me understand that, yes, I really do enjoy spending all my time doing research in a lab.”
The combination of Leconte’s mentorship and the connections she made with fellow Scripps students affirmed that graduate school was the path Barrett wanted to take. She is currently doing critical research on lasso peptides to assist in therapeutic drug development, for which she received a prestigious National Science Foundation Graduate Research Fellowship. Lasso peptides, Barrett explains, possess an organized structure which makes them highly stable in different environments. When administered orally, many therapeutic peptide drugs encounter enzymes called proteases in the stomach’s highly acidic environment and in the bloodstream, which can cause the drug to degrade. But, because lasso peptides are highly structured, they are resistant to the protease problem, allowing drugs to be more effective. Barrett’s project seeks to understand the substrate tolerance of lasso peptide cyclases, which are the enzymes responsible for tying peptides into the characteristic, organized lasso peptide shape. She hopes to uncover the rules regarding which peptide sequences can be tied into lassos, and which cannot.
“Our hope is that once we understand all the substrate tolerance rules, we can begin to engineer cyclases to accept a wider range of sequence substrates and create larger, more diverse libraries of lasso peptides that we can screen against therapeutic targets,” Barrett explains.
Growing up in St. Louis, Missouri, Barrett recalls the influence of one high school physics teacher who thought women shouldn’t go into science. Scripps’ community of predominantly women in STEM provided her with an empowering experience.
“Going to Scripps and being surrounded by women-identifying peers and faculty members set me on a new trajectory,” says Barrett. “My experience gave me the confidence to go to graduate school and pursue a PhD.”
In particular, the insights gained through Scripps’ Core Curriculum in Interdisciplinary Humanities have stayed with Barrett as she has navigated post-graduation life. The theme of her Core I course focused on violence, which she says has helped her identify the harm that institutions can inflict upon different marginalized groups.
“Without that class, I don’t know if I necessarily would have thought about it much in graduate school and beyond,” she says. “I want to make changes within my current and future departments by instituting new policies and practices, and creating spaces in STEM that are more inclusive and supportive.”
Barrett says the College’s emphasis on interdisciplinary science and the holistic value of its students has inspired her long-term career ambitions as well. She aims to become a professor at a primarily undergraduate institution like Scripps.
“Scripps has shaped the type of professor I want to be—one that brings cultural relevance into the classroom to motivate students and thinks more creatively about ways we teach STEM,” she says. “Scripps showed me that education can be creative and interdisciplinary in a way I’d never thought of before, and that’s something I want to do for the rest of my life.”