Radiation induced decomposition of tryptophan in the presence of oxygen

Josimović, Lj.; Janković, Ivana A.; Jovanović, Slobodan V.

doi:10.1016/0969-806x(93)90029-t

Cited by 26 publications

(10 citation statements)

References 21 publications

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“…3a transients absorb at each wavelength, it is not possible to measure accurately the lifetime of either species under these conditions. Tryptophan and indole cation radicals have reported pK, values of 4.3 and 4.6-4.9, respectively (32, [35][36][37]. Thus, at neutral and alkaline pH we expect equilibrium reaction 5 to favor the neutral radical.…”

Section: Transient Absorption Spectramentioning

confidence: 97%

“…Indole and its derivatives, especially Trp, have been the subject of intensive photolytic (1-30) and radiolytic (29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39) investigations. The aim of most of these studies has been to obtain a better understanding of the photo-and radiation chemistry of Trp, as well as of phenylalanine and tyrosine, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…As this study shows, its behavior is remarkably similar to that of the other two analogs, especially with respect to the deprotonation of the cation radical. Scheme 1 shows the proposed initial ioniza-(3 2, [35][36][37].…”

Section: Introductionmentioning

confidence: 99%

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Photoionization of Indole, N‐Methylindole and Tryptophan In Aqueous Solution upon Excitation at 193 nm

McGimpsey

Görner

1996

Photochem & Photobiology

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Abstract— The 193 nm photoionization of aqueous indole, A'‐meth‐ylindole and tryptophan–as a function of pH and under several saturating gas conditions–has been studied by laser photolysis using optical and conductometric detection methods. Monophotonic ionization leads to production of the cation radicals and hydrated electrons, the quantum yield of electron ejection is 0.3–0.4. The cation radicals have pKa values of 4.5, <5 and 4.5 for indole, N‐methylindole and tryptophan, respectively. Above these pH values, the cation radical deprotonate rapidly, having lifetimes of 1.0, ≅6 and 1.1 μs, respectively. Under N2O, neutral indolyl radical production is accompanied by formation of an OH adduct radical (<1 μs). The conductivity results in Ar‐ and N2O‐saturated solution support the deprotonation mechanism and indicate that in the acidic pH range, the cation radical decays by release of protons with kinetics on the millisecond time scale.

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Section: Transient Absorption Spectramentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Photoionization of Indole, N‐Methylindole and Tryptophan In Aqueous Solution upon Excitation at 193 nm

McGimpsey

Görner

1996

Photochem & Photobiology

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“…Oxidation of Trp can be very rapid, due to the low oxidation potential of this compound, and results in the formation of a wide range of materials including ring hydroxylated compounds (at the 2-, 4-, 5-, 6-, or 7-positions) and ring opened materials such as N-formylkynurenine, 3-hydroxykynurenine, kynurenine, and further oxidation products [68][69][70]. Some of these reactions occur via the initial formation of a neutral indolyl radical (itself formed via the ring radical-cation, or addition/elimination reactions [68,70]), and subsequent reaction with 0 2 .…”

Section: Aromatic Side-chainsmentioning

confidence: 99%

Stable Markers of Oxidant Damage to Proteins and Their Application in the Study of Human Disease

DAVIES¹,

FU²,

WANG³

et al. 2001

Bio-Assays for Oxidative Stress Status

117

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The mechanisms of formation and the nature of the altered amino acid side chains formed on proteins subjected to oxidant attack are reviewed. The use of stable products of protein side chain oxidation as potential markers for assessing oxidative damage in vivo in humans is discussed. The methods developed in the authors laboratories are outlined, and the advantages and disadvantages of these techniques compared with other methodologies for assessing oxidative damage to proteins and other macromolecules. Evidence is presented to show that protein oxidation products are sensitive markers of oxidative damage, that the pattern of products detected may yield information as to the nature of the original oxidative insult, and that the levels of oxidized side-chains can, in certain circumstances, be much higher than those of other markers of oxidation such as lipid hydroperoxides.

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“…Autooxidation propagated by peroxy radicals is a chain reaction. The initial phase is the reaction of HO • with tryptophan across the double C=C bonds, yielding Trp-OH adducts [93]. These adducts react with oxygen to produce the corresponding peroxy radicals.…”

Section: Rsh + Homentioning

confidence: 99%