Researchers at Florida State University's National High Magnetic Field Laboratory and Scripps Florida have developed and evaluated a robust new system for analyzing how drugs bind to proteins. This groundbreaking work could speed the delivery of potential new drugs and improve existing ones.
The work, which appears this week in the journal Analytical Chemistry, is the first published paper to result from a partnership between Scripps and a Florida university.
Scripps Florida is a state-of-the-art biomedical research institute currently located in Jupiter, Fla., on the campus of Florida Atlantic University. Scripps announced Florida would be home to its second facility in 2003, with the Florida Legislature agreeing to appropriate $310 million for the organization's start-up costs.
The National Science Foundation-funded magnet lab is the world leader in high-magnetic-field research and magnet development. Its facilities -- with branches at FSU, the University of Florida and Los Alamos National Laboratory in New Mexico -- are used by faculty and visiting scientists for research in many disciplines, including biology and biochemistry.
The collaborative research is focused on getting a more accurate picture of human proteins, which are the target of most drugs. Understanding the nature of the interaction between a drug and a protein -- where the drug attaches and where it doesn't -- is one of the keys to drug research, because the exact placement of a drug can determine whether it enhances a natural biological function or counteracts it.
"By pairing the magnet lab's expertise in high-field research with Scripps' expertise in protein dynamics and drug development, we can create a kind of map that shows where drugs bind to the surface of proteins," said Alan G. Marshall, director of the lab's Ion Cyclotron Resonance (ICR) program and the Kasha Professor of Chemistry and Biochemistry at FSU. "We can do that because our technology is the best way to generate highly accurate pictures of tiny amounts of protein molecules."
The technology referenced by Marshall is a Fourier transform ICR mass spectrometer built around a 14.5-tesla superconducting magnet. A tesla is a unit of measurement of a magnetic field's strength. To illustrate the magnet's relative strength, an MRI machine is 1.5 tesla, and a refrigerator magnet is 0.0025 tesla. Marshall is the co-inventor of Fourier transform ICR, and his group is widely acknowledged as the world leader in the development of Fourier transform ICR techniques and applications.
Marshall said the experiment detailed in Analytical Chemistry can best be described as "molecular spray painting." Here's how it works:
The receptor protein with a drug stuck to it is dipped into a solvent called "heavy water" (deuterium oxide, or D2O). In the portions of the receptor that can exchange with heavy water (regions not involved in hydrogen bonding), the natural hydrogen atoms are gradually replaced by deuterium atoms, which increase the mass from 1 to 2 mass units. Scientists then dissect the receptor and use the magnet to weigh pieces of it to see which segments of the receptor remain covered up by the drug.
The team saw the potential of probing human protein molecules with this spray-painting technique, but also recognized that the experiment was limited by several factors. Each test that would have to be performed would take anywhere from one minute to several hours, and each measurement would be slow. To ensure the reliability of the experiment, the process would need to be replicated twice more to validate the results, adding additional days to the process.