A cheetah lies still in the grass. Finally, a gazelle comes into view. The cheetah plunges forward, reaches sixty-five miles per hour in three seconds, and has the hapless gazelle by the jugular in less than a minute. Then it must catch its breath, resting before eating.
A blue whale surfaces, blasting water high from its blowhole. It breathes in great gasps, filling its thousand-gallon lungs with air. Then it descends again to look for krill, staying below for 10, 20, even 30 minutes before taking another breath.
Both animals need oxygen, of course. And both depend on the protein myoglobin to store and then release that oxygen within their working muscles. But how they need oxygen differs. The whale must have enough to last a whole dive. Its muscles have a high concentration of myoglobin that delivers oxygen steadily. In contrast, the cheetah's myoglobin must perform like a fast-shooting cannon. The cheetah needs to suddenly take up and release large doses of oxygen to stoke its explosive speed.
How does myoglobin do all that? For decades, biologists have wondered how -- and with what atomic motions, exactly -- the folded structure of myoglobin allows it to hold and release oxygen.
Now, two physicists at the University of Vermont have an answer. They've developed a new way to peer into the inner workings of proteins and detect which specific atoms are at work. Their work was published in the Aug. 27 issue of the journal Physical Review Letters.
Using myoglobin as a test, the scientists were able to home in on the critical functional piece of the protein, separating it from the vast number of other "jigglings and wigglings of atoms" says William DeWitt, a UVM graduate student and the lead author on the paper that describes the finding.
"We've been able to identify the motion of one particular amino acid -- this group of atoms called the distal histidine -- that controls the binding process," he sa
|Contact: Joshua Brown|
University of Vermont