Gellman says the idea of replacing segments of the peptide backbone with artificial units once seemed heretical. "Most people expected that you could not change the backbone, which alters the spacing and orientation of the essential contact points, without making the molecule unrecognizable to the receptor."
Gellman has assigned his rights for the discovery to the Wisconsin Alumni Research Foundation. The study's first author, Cheloha, is a Ph.D. candidate in chemistry at UW-Madison. Co-author Thomas J. Gardella led a team at Harvard Medical School that conducted the biological assessments.
Potentially, the "alter-the-backbone" strategy could allow oral dosing of the rather fragile peptide drugs, which today must be injected to avoid destruction in the stomach and small intestine. By protecting the drugs from degrading enzymes, the new approach could also help sustain higher drug concentrations in the bloodstream.
The altered backbone also seems to make minor changes in signals that the receptor, once activated, transmits into the cell, Gellman says. "Changing the sites of backbone modification results in different profiles of response. Building drug molecules that activate only a certain type of response might allow us to dial out undesired side effects; but that's just a hope at this point."
To date, much of the focus on drug development has concerned the external features of signaling molecules, which directly contact a receptor, Gellman says. "The traditional approach is to keep the skeleton the same and modify the surface components. Our approach is just the opposite, keep the surface components the same, and modify the skeleton. Now that it is clear that this no
|Contact: Sam Gellman|
University of Wisconsin-Madison