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Scientists puzzle over whether DNA can conduct electric current

Three research groups looking into the idea that the DNA molecule could transport electric charges have published their results in Angewandte Chemie.

The idea came to chemists quite early. The building blocks of DNA, the base pairs, which are stacked within the spiral stairca...
Three research groups looking into the idea that the DNA molecule could transport electric charges have published their results in Angewandte Chemie.

The idea came to chemists quite early. The building blocks of DNA, the base pairs, which are stacked within the spiral staircase-like molecule, are packed so densely together that their electron clouds come very close to each other - almost like in a metal. Nevertheless, experiments to verify the conductivity of DNA give contradictory results, as in the following examples:

- The groups working with Michael G. Hill of Occidental College in Los Angeles and Jacqueline K. Barton of Caltech examined short pieces of DNA, which were attached vertically on a gold surface. In this way, they could measure conductivity along the length of the molecule - independent of the length of the DNA section;
- In contrast, other measurements carried out by Anthony Harriman at Louis-Pasteur University in Strasbourg make it "very clear" that DNA "is a relatively poor conductor of electrons."

The results are contradictory because the conductivity of DNA also depends on its composition, and, above all, on the order of its building blocks, suspects Bernd Giese, who teaches chemistry at the University of Basle. The electrons do not flow through DNA exactly as in a cable; rather they must hop from base to base. However, not all bases make equally good destinations; for example, positive charges can jump only from guanine to guanine (the other three bases thymine, adenine, and cytosine are out of the question for this). The conductivity of the DNA "wire" thus depends on the distribution of these guanine bases - the closer together they are, the easier it is for the charge to jump from base to base.

If special DNA did indeed conduct electricity, it may be possible to use this robust molecule to wire tiny machines. Moreover, defective DNA could be recognized by its conductivity.

This debate will certainly continue to keep us in suspense for quite some time, according to Angewandte Chemie.

Subjects

Life Sciences
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