ALBUQUERQUE, N.M -- A discovery linking the shape of a unit called the heme in a protein to protein function may prove useful in a range of scientific advances, including finding cures for diseases and cleaning up pollutants, says discoverer John Shelnutt, a physicist at the Department of Energy's Sandia National Laboratories. The first time such a correlation has been made, the discovery is being heralded by the biochemical and biophysical communities as one of the most intriguing new findings about proteins in recent years.
Proteins -- strings of amino acids -- are found in all living cells and are where the work of a cell occurs. The heme, which consists of a ring of carbons and nitrogens, is the portion of a "hemoprotein" that clasps the protein's iron atom in place. A single protein may contain as few as one heme or as many as ten.
"Before, people always thought the heme's primary function was to simply hold the iron in the protein so that the iron could carry out some biochemical reaction," Shelnutt says. "They weren't aware that the heme acted as part of the protein 'machine' and changed shape or even had shape. Many even believed it was flat [which it is outside the protein]. We've shown that that inside the protein the heme is three-dimensional, or nonplanar, and its shape corresponds to function."
Further, he's demonstrated that in many instances the heme's shape changes as it performs its job. "The main thing my discovery has done is provide a new way to look at hemeproteins and what they do," he says. "We're revealing previously hidden influences of the protein on the heme structure." Shelnutt says that initially his findings were so startling that when he first tried to publish his results "no one believed me or would publish them."
His observations finally appeared in a 1998 issue of Biophysical Journal. Since
then, his research has captured the interest of the biochemical and biophysical
communities. At a March meeting of the A
Contact: Chris Burroughs
DOE/Sandia National Laboratories