Water is indispensable to the chemistry of life, and scientists at the University of California, Berkeley, have made a significant step toward understanding why.
With the help of a novel mathematical technique they developed, a team of UC Berkeley chemists has discovered the source of water's unique ability to ionize weak acids and bases and set the stage for more complex reactions.
Among these weak acids and bases are the nucleic acids that comprise DNA and some of the amino acids that form the backbone of proteins.
"Ionization is just pulling protons off of molecules, and shuttling protons around an aqueous solution is basic to life," said theoretical chemist David Chandler, professor of chemistry at UC Berkeley.
The theoretical results found by Chandler and his colleagues, an international collaboration between scientists in Germany, former post-doctoral fellows and a graduate student in Chandler's group at UC Berkeley, were published in the March 16 issue of Science.
The molecular details of these ionization processes have never been measured before because the event is so rare - once an hour for any given molecule - and when it does happen it's over quickly, on the order of a trillionth of a second. Yet, the separation of a proton - a hydrogen atom missing its one electron - from a molecule is the essential first step in all acid/base chemical reactions.
"If you're sitting on top of a water molecule, only one in a billion water molecules would exhibit this phenomenon of charge separation at a given instant," Chandler said. "It sounds like a very rare occurrence, but this charge separation is critical to the way human beings live."
All organic molecules consist of a tinker-toy backbone of mostly carbon, nitrogen and oxygen with lots of hydrogen atoms stuck on like Christmas ornaments. When weak acids or bases land in a pool of water, according to the team's calculations, these hydrogen atoms act as i
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Contact: Robert Sanders
rls@pa.urel.berkeley.edu
510-643-6998
University of California - Berkeley
18-Mar-2001