| RESEARCH |
Lasers move H2O between H-bonding sites © SCIENCE 2005 A laser-initiated method has been used to measure the energy required to move a water molecule from one hydrogen-bonding site on an amide molecule to another one on the same molecule. This experimental information--and subsequent calculations of the water molecule's favored path--will better the understanding of how the amide backbone of proteins interacts with its watery environment and may improve computational simulations of biological processes. Timothy S. Zwier and colleagues at Purdue University first prepared discrete gas-phase clusters containing a single water molecule hydrogen-bound to either the amide NH or the amide carbonyl of trans-formanilide. They then used lasers to selectively excite one of these isomers, causing its water molecule to move to the other site [Science, published online Feb. 3, http://dx.doi.org/10.1126/science.1106977]. By doing so, Zwier's team was able to measure the energy required to move the water molecule in either direction. Kenneth D. Jordan and coworkers at the University of Pittsburgh then used calculations to verify this energy and to locate the path the water molecule takes (time-lapse image shown above). |
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