Sequence-dependent emission from stacked forms of ApC and CpA Evidence for stacked base (‘dimer’) absorption and left-handed stacked conformation

Daniels, Malcolm; Shaar, Casey S.; Morgan, James P.

doi:10.1016/0301-4622(88)87009-1

Cited by 10 publications

(10 citation statements)

References 11 publications

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“…We have recently reported such a reduction of r for the excimer formed by poly(dA-dT).poly(dA-dT) (Ge and Georghiou, 1991a) and discussed it in terms of (i) rotation of the bases in order for them to achieve the most favorable orientation and (ii) strong perturbations caused by the operation of charge-resonance andlor excitonresonance interactions, which are known to be responsible for excimer stability (Birks, 1970). A low r value was also reported for the excimer formed by the dinucleotide ApC (Daniels et al, 1988). [In this regard, the observed independence of r of the emission wavelength (see first footnote) for the polynucleotide in buffered solution suggests that no excimers are formed in that case; thus, the long tail in the spectrum (Fig.…”

Section: The Data Show That the Value Of Q/agmentioning

confidence: 98%

ROOM‐TEMPERATURE STEADY‐STATE FLUORESCENCE PROPERTIES OF POLY(dG‐dC).SPOLY(dG‐dC)

Huang¹,

Georghiou²

1992

Photochem & Photobiology

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We report the steady-state fluorescence properties of the alternating polynucleotide poly(dG-dC).poly(dG-dC) in low-salt solution at room temperature for excitation at the Hg lines 265, 280 and 297 nm. Its fluorescence spectrum peaks at about 325 nm and, within the experimental error, its shape does not change significantly with the excitation wavelength. The fluorescence anisotropy is found to decrease strongly for short-wavelength excitation, a behavior which is very similar to that exhibited by free guanine. In view of the fact that the anisotropy for free cytosine is virtually constant at the aforementioned three excitation wavelengths, the results suggest that in this polynucleotide the emission stems from guanine. The values of the fluorescence quantum yield for the three excitation wavelengths are found to be very low, 0.8 x 10(-5), 0.8 x 10(-5), and 2.8 x 10(-5), respectively; these are compatible with transfer of energy from the lower-energy electronic state of guanine, before vibronic relaxation is established, to cytosine. Upon denaturation, the fluorescence spectrum becomes very broad and the fluorescence quantum yield increases; these observations support the authenticity of the emission from the nondenatured polynucleotide.

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Section: The Data Show That the Value Of Q/agmentioning

confidence: 98%

ROOM‐TEMPERATURE STEADY‐STATE FLUORESCENCE PROPERTIES OF POLY(dG‐dC).SPOLY(dG‐dC)

Huang¹,

Georghiou²

1992

Photochem & Photobiology

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“…For every emission wavelength, the corresponding fluorescence intensities Fl and F2 are given by 7 Such strong interactions occur in some dinucleoside phosphates (Daniels et al, 1988). Fl = fiF and F2 = f2F, where F is the total fluorescence intensity at that wavelength.…”

Section: Pap 5 4~2 -5mentioning

confidence: 99%

EXCITED‐STATE PROPERTIES OF THE ALTERNATING POLYNUCLEOTIDE POLY(dA‐dT)POLY(dA‐dT)

Georghiou

1991

Photochem & Photobiology

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Measurements of the steady-state fluorescence spectrum and anisotropy, r, of the alternating polynucleotide poly(dA-dT).poly(dA-dT) were carried out in order to characterize its photophysical properties at room temperature. The shape of the fluorescence spectrum depends on the excitation wavelength, namely, the relative fluorescence intensity of the short-wavelength peak decreases for excitation at short wavelengths. When monitoring the emission at short wavelengths, r is 0.18 and independent of the excitation wavelength. When monitoring the emission at long wavelengths, however, r is very low, about 0.03. These results suggest that: (i) the short-wavelength emission stems from thymine; and (ii) the long-wavelength emission stems from an excited-state complex (excimer), with the same one being formed regardless of whether thymine or adenine is excited. The corresponding fluorescence spectra have been resolved. The occurrence of transfer of electronic energy is discussed.

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“…Experimental section), the extra phosphate of d(pApG) compared to d(ApG) does not alter the relevant dual fluorescence properties of the dinucleotide. 1, [40][41][42][43][44][45][46] observed for the adenine dinucleotide d(ApA), where the excimer state revealed itself by its exceptionally long (z300-400 ps) uorescence lifetime. The selection of the mixed dinucleotide d(ApG) for investigation was further motivated by the observed large effects on the uorescence lifetimes upon substitution of an increasing number of adenines in a d(A) 20 strand by guanines.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast photo-initiated molecular quantum dynamics in the DNA dinucleotide d(ApG) revealed by broadband transient absorption spectroscopy

Stuhldreier

Temps

2013

Faraday Discuss.

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The ultrafast photo-initiated quantum dynamics of the adenine-guanine dinucleotide d(ApG) in aqueous solution (pH 7) has been studied by femtosecond time-resolved spectroscopy after excitation at lambda = 260 nm. The results reveal a hierarchy of processes on time scales from tau < 100 fs to tau > 100 ps. Characteristic spectro-temporal signatures are observed indicating the transformation of the molecules in the electronic relaxation from the photo-excited state to a long-lived exciplex. In particular, broadband UV/VIS excited-state absorption (ESA) measurements detected a distinctive absorption by the excited dinucleotide around lambda = 335 nm, approximately 0.5 eV to the blue compared to the maximum of the broad and unstructured ESA spectrum after excitation of an equimolar mixture of the mononucleotides dAMP and dGMP. A similar feature has been identified as signature of the excimer in the dynamics of the adenine dinucleotide d(ApA). The lifetime of the d(ApG) exciplex was found to be tau = 124 +/- 4 ps both from the ESA decay time and from the ground-state recovery time, far longer than the sub-picosecond lifetimes of excited dAMP or dGMP. Fluorescence-time profiles measured by the up-conversion technique indicate that the exciplex state is reached around approximately 6 ps after excitation. Very weak residual fluorescence at longer times red-shifted to the emission from the photo-excited state shows that the exciplex is almost optically dark, but still has enough oscillator strength to give rise to the dual fluorescence of the dinucleotide in the static fluorescence spectrum.

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Sequence-dependent emission from stacked forms of ApC and CpA Evidence for stacked base (‘dimer’) absorption and left-handed stacked conformation

Cited by 10 publications

References 11 publications

ROOM‐TEMPERATURE STEADY‐STATE FLUORESCENCE PROPERTIES OF POLY(dG‐dC).SPOLY(dG‐dC)

ROOM‐TEMPERATURE STEADY‐STATE FLUORESCENCE PROPERTIES OF POLY(dG‐dC).SPOLY(dG‐dC)

EXCITED‐STATE PROPERTIES OF THE ALTERNATING POLYNUCLEOTIDE POLY(dA‐dT)POLY(dA‐dT)

Ultrafast photo-initiated molecular quantum dynamics in the DNA dinucleotide d(ApG) revealed by broadband transient absorption spectroscopy

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