Enantiomeric Conformation Controls Rate and Yield of Photoinduced Electron Transfer in DNA Sensitized by Ru(II) Dipyridophenazine Complexes.
Photosensitized oxidation of guanine is an important route to DNA damage. Ruthenium polypyridyls are very useful photosensitizers, as their reactivity and DNA-binding properties are readily tunable. Here we show a strong difference in the reactivity of the two enantiomers of [Ru(TAP)2(dppz)](2+), by using time-resolved visible and IR spectroscopy. This reveals that the photosensitized one-electron oxidation of guanine in three oligonucleotide sequences proceeds with similar rates and yields for bound Δ-[Ru(TAP)2(dppz)](2+), whereas those for the Λ enantiomer are very sensitive to base sequence. It is proposed that these differences are due to preferences of each enantiomer for different binding sites in the duplex.
†School of Chemistry, Trinity College, Dublin 2, Ireland.|‡Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, United Kingdom.
Páraic M
PM
Keane
†School of Chemistry, Trinity College, Dublin 2, Ireland.|§Trinity Biomedical Sciences Institute, Pearse Street, Dublin 2, Ireland.
Fergus E
FE
Poynton
‡Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, United Kingdom.|∥Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0QX, United Kingdom.
James P
JP
Hall
⊥Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Oxfordshire, OX11 0QX, United Kingdom.
Ian P
IP
Clark
⊥Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Oxfordshire, OX11 0QX, United Kingdom.
Igor V
IV
Sazanovich
⊥Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Oxfordshire, OX11 0QX, United Kingdom.
Michael
M
Towrie
†School of Chemistry, Trinity College, Dublin 2, Ireland.|§Trinity Biomedical Sciences Institute, Pearse Street, Dublin 2, Ireland.
Thorfinnur
T
Gunnlaugsson
#School of Chemistry and Chemical Biology, University College Dublin, Dublin 4, Ireland.
Susan J
SJ
Quinn
‡Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, United Kingdom.
Christine J
CJ
Cardin
†School of Chemistry, Trinity College, Dublin 2, Ireland.
John M
JM
Kelly
D004247:DNA / Q000737:chemistry*; D004579:Electron Transport; D004583:Electrons; D012428:Ruthenium / Q000737:chemistry*; D013237:Stereoisomerism
D012428:Ruthenium; D004247:DNA
guanine; metal complexes; nucleic acids; photo-oxidation; transient spectroscopy