Intraprotein electron transfer and proton dynamics during photoactivation of DNA photolyase from E. coli: review and new insights from an "inverse" deuterium isotope effect.
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 In addition, we present unpublished data on the charge recombination between the fully reduced FADH(-) and the neutral (deprotonated) radical of the solvent exposed tryptophan W306.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.
Byrdin
Martin
M
Service de Bioénergétique, CEA, and URA 2096 CNRS, CEA Saclay, Bat. 532, F-91191 Gif-sur-Yvette Cedex, France. byrdin@dsvidf.cea.fr
Sartor
Valérie
V
Eker
André P M
AP
Vos
Marten H
MH
Aubert
Corinne
C
Brettel
Klaus
K
Mathis
Paul
P
D004255:Deoxyribodipyrimidine Photo-Lyase / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects; D003903:Deuterium / Q000737:chemistry; D004579:Electron Transport; D004734:Energy Metabolism; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D008954:Models, Biological; D018462:Photobiology; D018892:Proton-Motive Force; D013053:Spectrophotometry; D014364:Tryptophan / Q000737:chemistry
D014364:Tryptophan; D003903:Deuterium; D004255:Deoxyribodipyrimidine Photo-Lyase