Intraprotein electron transfer and proton dynamics during photoactivation of DNA photolyase from E. coli: review and new insights from an "inverse" deuterium isotope effect

Biochim Biophys Acta. 2004 Apr 12;1655(1-3):64-70. doi: 10.1016/j.bbabio.2003.07.001.

Abstract

We review our work on electron transfer and proton dynamics during photoactivation in DNA photolyase from E. coli and discuss a recent theoretical study on this issue. In addition, we present unpublished data on the charge recombination between the fully reduced FADH(-) and the neutral (deprotonated) radical of the solvent exposed tryptophan W306. We found a pronounced acceleration with decreasing pH and an inverse deuterium isotope effect (k(H)/k(D)=0.35 at pL 6.5) and interpret it in a model of a fast protonation equilibrium for the W306 radical. Due to this fast equilibrium, two parallel recombination channels contribute differently at different pH values: one where reprotonation of the W306 radical is followed by electron transfer from FADH(-) (electron transfer time constant tau(et) in the order of 10-50 micros), and one where electron transfer from FADH(-) (tau(et)=25 ms) is followed by reprotonation of the W306 anion.

Publication types

  • Review

MeSH terms

  • Deoxyribodipyrimidine Photo-Lyase / chemistry
  • Deoxyribodipyrimidine Photo-Lyase / metabolism*
  • Deoxyribodipyrimidine Photo-Lyase / radiation effects
  • Deuterium / chemistry
  • Electron Transport
  • Energy Metabolism
  • Escherichia coli / enzymology
  • Kinetics
  • Models, Biological
  • Photobiology
  • Proton-Motive Force
  • Spectrophotometry
  • Tryptophan / chemistry

Substances

  • Tryptophan
  • Deuterium
  • Deoxyribodipyrimidine Photo-Lyase