A porphyrin-DNA exciplex: resonance Raman spectra of electronically excited Cu(TMpy-P4) bound to poly(dA-dT).poly(dA-dT).
The resonance Raman spectra of water-soluble porphyrins, Cu(TMpy-P4) and Ni(TMpy-P4), and their mixtures with DNA, Poly(dG-dC).Poly(dG-dC), and Poly(dA-dT).Poly(dA-dT) were measured using 426 nm pulsed laser excitation (and 556 nm for some applications). At high laser power, the solution of Cu(TMpy-P4) mixed with DNA or Poly(dA-dT).Poly(dA-dT) exhibits new bands at 1550 and 1349 cm-1 that are not observed for Cu(TMpy-P4) alone or for Cu(TMpy-P4) mixed with Poly(dG-dC).Poly(dG-dC). These extra bands do not appear when the resonance Raman spectra are measured by a cw laser or by a pulsed laser with low power. Similar mixtures of M(TMpy-P4) (where M = Ni, Zn, Co, Mn, and H2) with these nucleic acids exhibit no such bands even by high power pulsed laser excitation. We attribute the new resonance Raman bands to an electronically excited Cu(TMpy-P4), stabilized by forming an exciplex with the A-T site of the nucleic acid. The minimum lifetime value of such an exciplex was estimated to be on the order of 10 ps.
Turpin
P Y
PY
Institut Curie, Université Pierre et Marie Curie, Paris, France.
Chinsky
L
L
Laigle
A
A
Tsuboi
M
M
Kincaid
J R
JR
Nakamoto
K
K
D003300:Copper; D004247:DNA; D008652:Mesoporphyrins; D009532:Nickel; D011067:Poly dA-dT; D011089:Polydeoxyribonucleotides; D011166:Porphyrins; D013059:Spectrum Analysis, Raman / Q000379:methods; D013816:Thermodynamics
D008652:Mesoporphyrins; D011089:Polydeoxyribonucleotides; D011166:Porphyrins; D011067:Poly dA-dT; C021096:tetra(4-N-methylpyridyl)porphine; D003300:Copper; D009532:Nickel; D004247:DNA