Single-molecule DNA flexibility in the presence of base-pair mismatch

The conformational changes of a 22 base-pair double-stranded DNA, anchored via one end to a quartz substrate, have been characterized using a single-pair fluorescence resonance energy transfer technique. Base-pair mismatch, a major form of DNA damage, has been found to decrease the energy transfer between a fluorescence donor and an acceptor attached to the two ends of DNA molecules with 3 and 7 mismatches, by 4.4% and 10.4%, respectively, as compared to that for perfectly matched DNA. This result suggests that the disruption of the hydrogen bonds in damaged DNA leads to increased contour length and improved flexibility. (c) 2005 American Institute of Physics.