Photochemistry of uridine on high intensity laser UV irradiation

Khoroshilova, E. V.; Nikogosyan, David N.

doi:10.1016/1011-1344(90)85055-2

Cited by 24 publications

(17 citation statements)

References 15 publications

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“…by the absence of an oxygen effect on the products and their Q, values. This is in line with the general finding that photohydrates are formed by reaction with water in the S , state of the pyridine not involving T I (23,58,63). The quantum yield of the sum of the hydrates is 0.01 8, whereas that of dimers is smaller by an order of magnitude ( Table 1).…”

Section: Uridinesupporting

confidence: 91%

“…Kadical cations can also be produced photolytically by the action of vacuum-UV, e.g. with monochromatic synchrotron radiation (40)(41)(42)(43) or by a two-quanta-induced method with high-intensity far-UV irradiation, the wavelength is typically 248 or 266 nm (52)(53)(54)(55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65). The energy of the photons with hi,, = 193 nm (6.4 eV) corresponds to the transition to the second excited singlet state, So + S,, which is above the ionization limit.…”

Section: Introductionmentioning

confidence: 99%

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Depopulation of Highly Excited Singlet States of DNA Model Compounds: Quantum Yields of 193 and 245 nm Photoproducts of Pyrimidine Monomers and Dinucleoside Monophosphates

Gurzadyan¹,

Görner²

1996

Photochem & Photobiology

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Formation of uracil and orotic acid photodimers, uridine and 5'-UMP photohydrates, TpT photodimers and (6-4)photoproducts, dCpT photohydrates and (6-4)photoproducts and UpU, CpC and CpU photohydrates were studied in neutral deoxygenated aqueous solution at room temperature upon irradiation at either 193 or 254 nm. The photoproducts were identified and quantified and the contribution from photoionization to substrate decomposition, using lambda irr = 193 nm, was separated. The ratio of the quantum yields of respective stable products, eta = phi 193/phi 254, is indicative of the yield of internal conversion from the second to the first excited singlet state, S2-->S1. For the observed photodimers eta decreases from 0.94 for uracil to 0.7 for TpT and further to 0.55 for orotic acid. For the (6-4)photoproducts of TpT and dCpT eta = 0.5-0.8 and for the photohydrates in the cases of UpU, CpC, CpU and dCpT eta ranges from 0.55 to 1.

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Section: Uridinesupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Depopulation of Highly Excited Singlet States of DNA Model Compounds: Quantum Yields of 193 and 245 nm Photoproducts of Pyrimidine Monomers and Dinucleoside Monophosphates

Gurzadyan¹,

Görner²

1996

Photochem & Photobiology

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“…Figure 6 shows the normalized transient absorption spectra of an aqueous solution of Carbostyryl-124 (10 −5 M) 170 ps after the pump pulse for different peak irradiance of the pump pulse. These spectra show a negative absorption due to stimulated emission in the wavelength range 400-500 nm and an increased absorption in the range 520-700 nm, which is besides a broad absorption of the dye molecule in the S 1 -state typical for the formation of a solvated electron (broad absorption spectrum with a maximum at 720 nm) [28,30,31] and of a dye radical cation or deprotonated dye radical ion (absorption maximum: 630 nm) (Seidel and unpublished results [15]).…”

Section: Photobleaching Properties For Ope At a High Irradiancementioning

confidence: 99%

Laser‐induced fluorescence of coumarin derivatives in aqueous solution: Photochemical aspects for single molecule detection

Eggeling¹,

Brand²,

Seidel³

1997

Bioimaging

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The efficiency of detecting a single fluorescent coumarin dye molecule in aqueous solution by one‐photon excitation (OPE) at 350 nm as well as by coherent two‐photon excitation (TPE) at 700 nm is studied. The photostability, which is crucial for single molecule detection (SMD), is determined at a low irradiance for various coumarin derivatives using a ‘cell‐bleaching’ method. The yields of photobleaching for these coumarins in aqueous solution are in the order of 10−3 to 10−4. Thus, most of the dyes are sufficiently stable to allow SMD. However, for SMD in a fluorescence microscope a high quasi‐CW irradiance (at least 104 W cm−2) is necessary for efficient OPE by a pulsed, frequency doubled titanium:sapphire laser. Detailed investigations on the dye Coumarin‐120 using fluorescence correlation spectroscopy (FCS), different repetition rates of the laser and transient absorption spectroscopy (TRABS) gave clear evidence that OPE at a high irradiance results in two‐step photolysis via the first electronic excited singlet and triplet state, S1 and T1, producing dye radical ions and solvated electrons. Hence, this additional photobleaching pathway limits the applicable irradiance for OPE. Using coherent TPE for single molecule detection, saturation of the fluorescence was observed for a high quasi‐CW irradiance (108 W cm−2), which may also be caused by photobleaching. Furthermore, TPE is deteriorated by other competing nonlinear processes (e.g. continuum generation in the solvent), which only occur above a threshold irradiance (7 × 107 W cm−2). Nevertheless, TPE allows an efficient detection of single Coumarin‐120 molecules in water. Using a maximum likelihood estimator, we are also able to identify single dye molecules via their characteristic fluorescence lifetime of 4.8 ± 1.2 ns.

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“…Thus, photoionization mimics the direct effect of high energy radiation. In addition, several stable photoproducts, such as cyclobutane-type dimers, hydrates and photoadducts, not originating from radicals, are known from irradiation of pyrimidines at 254 nm.9J0, [23][24][25][26][27][28][29][30][31][32][33] Purines, which do not yield these products, are generally less sensitive to UV irradiation than pyrimidine^.^^^^^^^^ A specific photodimerization reaction has been reported for adenine-containing compounds.344z…”

Section: Introductionmentioning

confidence: 99%

Damage to Uracil‐ and Adenine‐containing Bases, Nucleosides, Nucleotides and Polynucleotides: Quantum Yields on Irradiation at 193 and 254 Nm

Gurzadyan

Görner

1994

Photochem & Photobiology

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Photoreactions, such as base release and decomposition of the base moiety, induced by either 20 ns laser pulses at 193 nm or continuous 254 nm irradiation, were studied for a series of uracil and adenine derivatives in neutral aqueous solution. The quantum yield of chromophore loss (phi cl) depends significantly on the nature of the nucleic acid constituent and the saturating gas (Ar, N2O or O2). In the case of polynucleotides the destruction of nucleotides was measured by high-performance liquid chromatography after hydrolysis; the quantum yields (phi dn) are comparable to those of chromophore loss or larger. The phi cl and phi dn of 0.04-0.1 for poly(U) and poly(dU), obtained for both wavelengths of irradiation, are due to processes originating from the lowest excited singlet state, i.e. formation of photohydrates and photodimers, and a second part from photoionization using lambda irr = 193 nm. Irradiation at 193 nm effectively splits pyrimidine dimers and thus reverts them into monomers. The quantum yield for release of undamaged bases (phi br) from nucleosides, nucleotides and polynucleotides upon irradiation at 254 nm is typically phi br = (0.1-1) x 10(-4). Breakage of the N-glycosidic bond is significantly more efficient for lambda irr = 193 nm, e.g. phi br = 1.1 x 10(-3), 0.8 x 10(-3), 4.3 x 10(-3) and 0.5 x 10(-3) for poly(A), poly(dA), poly(U) and poly(dU) in Ar-saturated solution, respectively. Enhanced phi values for lambda irr = 193 nm, essentially for adenine and its derivatives, are caused by photoprocesses that are initiated by photoionization.

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Photochemistry of uridine on high intensity laser UV irradiation

Cited by 24 publications

References 15 publications

Depopulation of Highly Excited Singlet States of DNA Model Compounds: Quantum Yields of 193 and 245 nm Photoproducts of Pyrimidine Monomers and Dinucleoside Monophosphates

Depopulation of Highly Excited Singlet States of DNA Model Compounds: Quantum Yields of 193 and 245 nm Photoproducts of Pyrimidine Monomers and Dinucleoside Monophosphates

Laser‐induced fluorescence of coumarin derivatives in aqueous solution: Photochemical aspects for single molecule detection

Damage to Uracil‐ and Adenine‐containing Bases, Nucleosides, Nucleotides and Polynucleotides: Quantum Yields on Irradiation at 193 and 254 Nm

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