Electron transfer between bases in double helical DNA.
Fluorescent analogs of adenine that selectively oxidize guanine were used to investigate photoinduced electron transfer through the DNA pi-stack as a function of reactant stacking and energetics. Small variations in these factors led to profound changes in the kinetics and distance dependences of DNA-mediated electron-transfer reactions. Values of beta, a parameter reflecting the dependence of electron transfer on distance, ranged from 0.1 to 1.0 per angstrom. Strong stacking interactions result in the fastest electron-transfer kinetics. Electrons are thus transported preferentially through an intrastrand rather than interstrand pathway. Reactant energetics also modulate the distance dependence of DNA-mediated charge transport. These studies may resolve the range of disparate results previously reported, and paradigms must now be developed to describe these properties of the DNA pi-stack, which can range from insulator- to "wire"-like.
Kelley
S O
SO
Beckman Institute, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Barton
J K
JK
D015075:2-Aminopurine / Q000737:chemistry; D000225:Adenine / Q000031:analogs & derivatives / Q000737:chemistry; D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D004583:Electrons; D006147:Guanine / Q000737:chemistry; D006860:Hydrogen Bonding; D007700:Kinetics; D008027:Light; D009690:Nucleic Acid Conformation; D010084:Oxidation-Reduction; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
C004981:1,N(6)-ethenoadenine; D015075:2-Aminopurine; D006147:Guanine; D004247:DNA; D000225:Adenine