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

Biochimica et biophysica acta (2004-04-22)
Martin Byrdin, Valérie Sartor, André P M Eker, Marten H Vos, Corinne Aubert, Klaus Brettel, Paul Mathis
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 In addition, we present unpublished data on the charge recombination between the fully reduced FADH(-) and the neutral (deprotonated) radical of the solvent exposed tryptophan W306.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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Deuterium, 99.8 atom % D
Sigma-Aldrich
Deuterium, 99.96 atom % D
Sigma-Aldrich
Deuterium, 99.9 atom % D