Tucson researcher receives national award

March 21, 2000

Recognized for insight gained through research on the kissing bug

Chemist F. Ann Walker of Tucson, Ariz., will be honored on March 28 by the world's largest scientific society for furthering understanding of how heme proteins work -- insight gained through research on the 'kissing bug,' a blood-sucking insect. She will receive the Francis P. Garvan-John M. Olin Medal, which recognizes distinguished service to chemistry by women chemists, from the American Chemical Society at its national meeting in San Francisco.

Heme proteins -- a class of molecules that includes hemoglobin and components of the immune system - function as the body's delivery service. Some heme proteins ferry gases: for example, the iron center of hemoglobin delivers oxygen to cells. Others carry electrons plucked from food, which cells use as energy to maintain body temperature, run reactions, and more.

Walker, an inorganic chemist at the University of Arizona, asked why so many heme proteins exist and why they differ so much. "What are the particular features around the iron center's electrons that will help me understand why it was chosen for a particular task?" she summarized.

That question led her to the kissing bug of the Amazon river basin. In 1991 Walker was a member of the research team that discovered a new class of heme proteins in the saliva of the blood-sucking insect. In a display of clever evolution, the kissing bug injects a heme protein called nitrophorin as it bites. Once in the victim's tissue, nitrophorin's iron center releases nitric oxide. Like nitroglycerin, a drug used to relieve chest pain, nitric oxide causes blood vessels to dilate.

In response to this intrusion, surrounding cells release histamine. Nitrophorin binds and inactivates these histamine molecules, increasing the kissing bug's chance of dining undisturbed on a more plentiful meal.

Hemogloblin shares nitrophorin's iron center, but not its ability to release nitric oxide. Walker probed the natural resonance of nuclei within the molecule and found out why: the electron structure that surrounds nitrophorin's iron center is more oxidized than that of hemoglobin.

"I doubt there's ever going to be a heart-attack drug from nitrophorin, but just learning exactly how it works is enlightening," said Walker.

The ACS Francis P. Garvan-John M. Olin Medal is sponsored by the Olin Corp. Charitable Trust of Norwalk, Conn. The award is named for Francis Patrick Garvan, president of the Chemical Foundation from 1919-1937, and John Merrill Olin, a chemical engineer and former chairman of the board of Olin Corporation.
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A nonprofit organization with a membership of 161,000 chemists and chemical engineers, the American Chemical Society www.acs.org publishes scientific journals and databases, convenes major research conferences, and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.

American Chemical Society
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