The findings came as something of a surprise, despite earlier studies that have shown buckyballs to be toxic to cells unless coated and to be able to find their way into the brains of fish. Before these cautionary discoveries, researchers thought that the combination of buckyballs' dislike of water and their affinity for each other would cause them to clump together and sink to the bottom of a pool, lake, stream or other aqueous environment. As a result, researchers thought they should not cause a significant environmental problem.
Cummings' team found that, depending on the form the DNA takes, the 60-carbon-atom (C60) buckyball molecule can lodge in the end of a DNA molecule and break apart important hydrogen bonds within the double helix. They can also stick to the minor grooves on the outside of DNA, causing the DNA molecule to bend significantly to one side. Damage to the DNA molecule is even more pronounced when the molecule is split into two helices, as it does when cells are dividing or when the genes are being accessed to produce proteins needed by the cell.
"The binding energy between DNA and buckyballs is quite strong," Cummings says. "We found that the energies were comparable to the binding energies of a drug to receptors in cells."
It turns out that buckyballs have a stronger affinity for DNA than they do for themselves. "This research shows that if buckyballs can get into the nucleus, they can bind to DNA," Cummings says. "If the DNA is damaged, it can be inhibited from self-repairing."
Computer simulations
The computer simulations showed that buckyballs make first contact with the DNA molecule after one to two nanoseconds. Once the C60 molecules bind with the DNA, they remained stable for the duration of the simulation.
Researchers tested the most common forms of DNA, the "A" and "B" forms. The "B" form is the most common form. In a stronger saline solution,
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Contact: Vivian Cooper
vivian.f.cooper-capps@vanderbilt.edu
615-343-6314
Vanderbilt University
6-Dec-2005