Unique magnetic signatures of mismatched base pairs in DNA.

Magnetic properties of DNA containing mispairs, such as different conformations of the GA mispair, or a GT mispair inserted into the DNA chain, have been theoretically investigated. The essential ingredients for these studies, the charge transfer integrals, were evaluated from the DNA sequences containing the mispair and optimized in the solvent. We find that the magnetic susceptibilities of the host DNA chain containing a large number of Watson-Crick base pairs are significantly altered in the presence of the mispairs, and the effects depend on the choice of mispairs. In particular, insertion of even a single GA mispair changes the nature of magnetization (sign of the susceptibility) of the host DNA. We propose that measurement of the magnetic properties of DNA might provide a direct route to detection and identification of those mispairs.