Direct measurement of the dynamics of hole hopping in extended DNA G-tracts. An unbiased random walk.
We report the measurement of distance- and temperature-dependent rate constants for charge separation in capped hairpins in which a stilbene hole acceptor and hole donor are separated by A(3)G(n) diblock polypurine sequences consisting of 3 adenines and 1-19 guanines. The longer diblock systems obey the simplest model for an unbiased random walk, providing a direct measurement of k(hop) = 4.3 × 10(9) s(-1) for a single reversible G-to-G hole hopping step, somewhat faster than the value of 1.2 × 10(9) s(-1) calculated for A-tract hole hopping. The temperature dependence for hopping in A(3)G(13) provides values of E(act) = 2.8 kcal/mol and A = 7 × 10(9) s(-1), consistent with a weakly activated, conformationally gated process.
Conron
Sarah M Mickley
SM
Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208, USA.
Thazhathveetil
Arun K
AK
Wasielewski
Michael R
MR
Burin
Alexander L
AL
Lewis
Frederick D
FD
D004247:DNA / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry*; D007700:Kinetics; D013057:Spectrum Analysis; D013696:Temperature
D006147:Guanine; D004247:DNA