2025 Talented 12: Nick Riley

At a conference this spring, chemical biologist Nick Riley delivered a lightning talk in character as George Washington. Wearing a white powdered wig and accompanied by some members of his laboratory, he riffed on a popular Saturday Night Live sketch about US resistance to the metric system. But instead of expounding on inscrutable units of measure, Riley talked about the future of measuring glycans with mass spectrometry (MS).

Campy? Perhaps a little. Riley, who has always been an extrovert, isn’t afraid to have a little fun. But he’s serious about pursuing better ways to study the biochemistry of sugars that decorate cell surfaces. He hopes that someday scientists could analyze these sugars en masse to infer the health of the cell. For example, how does a cell’s surface change as it accumulates abnormalities—and how does its new surface chemistry promote a slide toward cancer?

Between three-quarters and nine-tenths of cell surface molecules sport glycan chains, scientists think. A glycoprotein might have many different sugar structures attached to many different amino acids within the protein, and these structures can be added, removed, or modified, rapidly adding up to thousands of unique chemical species.

The abundance of different species is just one reason glycoproteins are hard to analyze. Another is that glycoproteins feature two incongruous chemistries—proteins and sugars. That molecular discordance “changes everything about the chemistry we want to study,” Riley says, including how a molecule behaves within a mass spectrometer.

Biochemists often study proteins using MS because it allows them to determine a protein’s amino acid sequence by fragmenting it into smaller ions. The challenge is to get good data on the peptide and the glycan simultaneously. Historically, researchers have separated sugar from peptide and analyzed them separately with MS. Riley wants to keep the pieces assembled to retain information about where on a protein a given glycan is attached and how its presence might alter protein structure and binding.

Riley got interested in MS as an undergraduate researcher in a forensic chemistry lab. “I was asking a lot more questions about the instrument than I was about the experiments,” he recalls.

As a graduate student in Joshua Coon’s lab at the University of Wisconsin–Madison, Riley devised a new MS method for glycopeptide analysis that looks at both proteins and sugars at the same time. Riley demonstrated that combining two approaches, fragmentation by electron transfer dissociation and infrared irradiation, yields spectra with both sugar and peptide ions. It was “a big step” for the field, Coon says.

During a postdoctoral fellowship in Carolyn Bertozzi’s lab at Stanford University, Riley turned his attention from the N-linked glycans he had studied with Coon, which are bound to asparagine, to O-linked glycans, which are bound to serine or threonine. O-linked glycans are even more difficult to analyze because, compared with N-linked glycans, they are less likely to appear on specific amino acid sequences and they break down more easily. Riley devised fragmentation methods for the unique chemical requirements of O-glycans and developed software that uses MS data to reconstruct the fragmented glycopeptides.

Riley started his own lab at the University of Washington in 2023. His lab’s goal is to decode the patterns in protein sequence and cell signaling that determine when and where both N- and O-linked glycans are added to tune proteins’ functions. He also wants to find out how a cell’s glycans change as it transitions from healthy to diseased states.

When Riley started his research group, he launched a quarterly diversity, equity, and inclusion journal club to address science’s history of excluding people who belong to marginalized groups. As diversity-related programs have been scrapped in recent months, Riley’s lab members have asked if he planned to cancel the journal club. No, he said—it is needed now more than ever. He wants to continue to be a voice that champions the value of diversity in science, he says. “I’m not going away and not hiding behind anything.”

Back in the lab, Riley plans to continue to work on making glycan analysis easier. He likes hard technical problems. “That’s where the opportunity is,” he says. “That’s a cool space, as an analytical chemist and chemical biologist, to be.”