Russ Gibadullin was staring at a twisted ribbon of protein on his computer screen, the kind that textbooks say must coil into a perfect spiral for a drug like Forteo to work. But what he saw defied decades of assumption — the peptide wasn’t forming the classic alpha helix, and yet it was still activating its target receptor with surprising strength. At the University of Wisconsin–Madison, Gibadullin and his advisor, Professor Sam Gellman, had stumbled onto a discovery that could reshape how scientists think about peptide drugs, the molecular messengers behind treatments for diabetes, osteoporosis, and more. For years, researchers believed that drugs like Ozempic, Mounjaro, and Forteo needed to twist into a precise spiral shape — an alpha helix — to fit into their cellular receptors like a key in a lock. But the Gellman Group’s work shows that the lock can turn even when the key isn’t perfectly shaped.
This isn’t just academic curiosity; it’s a potential breakthrough in drug design. Many side effects of current peptide therapies stem from these drugs triggering multiple signaling pathways — some helpful, others not. The team’s modified peptides, engineered to resist forming the traditional spiral, still activated their target receptors powerfully but avoided certain secondary pathways. That selectivity, known as “biased agonism,” could lead to medications that are both more effective and safer. Lauren Tran, a current Ph.D. student in the group, confirmed the finding extended beyond glucagon to the parathyroid hormone receptor targeted by Forteo, suggesting this approach might work across a whole class of receptors known as class B1 GPCRs.
The implications ripple across pharmaceutical science. If a drug doesn’t need to maintain a rigid helical structure to be effective, chemists have far more freedom in designing stable, long-lasting versions. The team used a technique called heterochiral design — swapping natural amino acids for their mirror-image forms — to destabilize the spiral without losing potency. Their findings, published in Nature Chemistry (DOI: 10.1038/s41557-026-02182-x), challenge a long-held dogma and open new doors for engineering precision medicines. “That's what I would have guessed,” Gellman admitted, reflecting on the initial skepticism. “But the student who started this work had other ideas.”
Today, that idea is becoming a new principle. By decoupling receptor activation from strict structural requirements, the Madison team has given drug developers a new playbook. The next generation of peptide therapies might not look like what we’ve seen before — and that could be exactly what makes them better.