AT-dependent luminescence of DNA-threading ruthenium complexes.
Whereas the emission from the ruthenium complex deltadelta-[mu-bidppz(phen)4Ru2]4+ (P) is five times larger when intercalated into poly(dAdT)2 than when intercalated into ct-DNA, the homologue deltadelta-[mu-bidppz(bipy)4Ru2]4+ (B) has a smaller quantum yield and a red-shifted emission. The origin of this difference is here investigated by studying intercalation into oligonucleotides containing a central AT-tract. Increasing the length of the AT-tract increases the emission quantum yield for P but decreases it for B. However, not even four helix turns of AT base pairs is enough to mimic poly(dAdT)2. B and P thus use the increased flexibility with increasing length of the AT-tract in opposite ways, whereas B gets more prone to quenching by water, P gets more protected from quenching. The earlier reported gradual increase of the intercalation rate with AT-stretch length is thus paralleled by a gradual change in the equilibrium properties of the intercalated state.
Westerlund
Fredrik
F
Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden. fredrik.westerlund@chalmers.se
Lincoln
Per
P
D020029:Base Pairing; D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D007364:Intercalating Agents / Q000737:chemistry*; D049449:Luminescence; D015335:Molecular Probes; D009841:Oligonucleotides / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry*; D011067:Poly dA-dT; D012428:Ruthenium / Q000737:chemistry*; D013329:Structure-Activity Relationship
D007364:Intercalating Agents; D015335:Molecular Probes; D009841:Oligonucleotides; D009942:Organometallic Compounds; D011067:Poly dA-dT; D012428:Ruthenium; D004247:DNA