CHAPEL HILL - Got any valuable documents you want to preserve for posterity? Ancestors' U.S. immigration papers? Old letters? The family tree? The Declaration of Independence? The Magna Carta?
Now, a University of North Carolina at Chapel Hill scientist says his team's research suggests the best way is to keep them not only dry, but also cool. A book, for example, that might last a century at room temperature could stay in good shape for 600 years or more if kept away from moisture and simply cooled 10 degrees Celsius. Cooling papers further would extend their shelf life even more.
"We have been studying enzyme reactions and the natural process that breaks down covalent bonds which hold together compounds corresponding to the sugar building blocks of starch and cellulose," said Dr. Richard V. Wolfenden, Alumni Distinguished professor of biochemistry and biophysics at the UNC-CH School of Medicine. "Unexpectedly, we found that the decomposition, or hydrolysis, of these bonds is extremely sensitive to changing temperature and that refrigeration should provide a singularly effective means of preserving valuable documents."
A report on the research appears in the current (July 15) issue of the Journal of the American Chemical Society. Wolfenden's co-authors are graduate student Xiangdong Lu and Dr. Gregory Young, director of the UNC Biomolecular Nuclear Magnetic Resonance Facility.
The researchers found bonds holding cellulose -- the chief component of plant cell walls - and starch together to be remarkably stable, Wolfenden said. Under normal conditions, it would take 8 million years for half the bonds in cellulose to be broken and 5 million years for half the bonds in starch to decompose. By contrast, the half-lives of the covalent bonds that join DNA - the molecular blueprints for living things -- are 170,000 years and for proteins, 400 years.