Studies of the Triplet State of Proteins by Electron Spin Resonance Spectroscopy<sup>*</sup>

Shiga, Tetsuo; Hs, Mason; Simo, Constance

doi:10.1021/bi00870a014

Cited by 13 publications

(2 citation statements)

References 26 publications

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“…Tyr degradation was observed under solar simulator irradiation, which has greater UV-B intensity. Trp photodegradation was found to be highly concentration dependent, in agreement with previous reports of Trp self-quenching at micromolar concentrations (38). Thus all reported Trp photolyses were conducted at the lowest measurable Trp concentration of 250 nM.…”

Section: Resultssupporting

confidence: 91%

Indirect Photodegradation of Dissolved Free Amino Acids: The Contribution of Singlet Oxygen and the Differential Reactivity of DOM from Various Sources

Boreen

Edhlund

Cotner

et al. 2008

Environ. Sci. Technol.

210

189

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The role of photochemically generated singlet oxygen (1O2) in the DOM-sensitized degradation of eighteen dissolved free amino acids was investigated. The fraction of total sensitized degradation due to reaction with 1O2 was determined through a kinetic analysis based on a measured reaction rate constant for each amino acid coupled with measured 1O2 concentrations and was confirmed through quenching experiments. Only four of the eighteen free amino acid residues examined were found to be photolabile under environmentally relevant conditions: histidine, methionine, tyrosine, and tryptophan. The fraction of Suwannee River Humic Acid (SRHA)-sensitized degradation due to reaction with 1O2 ranged from an upper value of 110 +/- 10% for histidine to 8 +/- 1% for tryptophan, with 26 +/- 3% contribution for methionine and 33 +/- 4% for tyrosine. In addition to degradation through reaction with 1O2, other reactive intermediates involved in the SRHA-photosensitized degradation of these amino acids were identified. Methionine was thought to be additionally degraded through reaction with H2O2 and triplet excited-state DOM, and 67% of tyrosine's indirect photodegradation was assigned to an oxygen-dependent type I photooxidation reaction. The majority of tryptophan indirect degradation was due to reaction with 3DOM. Photodegradation experiments with various DOM sources including Pony Lake (Antarctica) fulvic acid and a synthetic estuarine sample, as well as Minnesota freshwater samples (lakes Itasca, Superior, Josephine, and the St Louis River), demonstrated distinct reactivity patterns, indicating that DOM's 1O2-generation efficiency is not strongly coupled to its ability to promote other photooxidation pathways. These four amino acids highlightthe differential photoreactivity of DOM from various sources.

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Section: Resultssupporting

confidence: 91%

Indirect Photodegradation of Dissolved Free Amino Acids: The Contribution of Singlet Oxygen and the Differential Reactivity of DOM from Various Sources

Boreen

Edhlund

Cotner

et al. 2008

Environ. Sci. Technol.

210

189

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“…Lion et al (1982), and also Mottley and Mason (1986) have observed similar spin adducts of carbon-centered radical from tryptophan or indole acetate. It is well known that UV-irradiation of tryptophan containing proteins produces tryptophan triplet state (Shiga and Piette, 1964;Shiga et al, 1966), which may be able to yield carbon-centered radicals by hydrogen abstraction. If such RC.…”

Section: (2) the Short-lived Radicals Trapped With D M P Omentioning

confidence: 99%

Near Uv‐induced Free Radicals in Ocular Lens, Studied by Esr and Spin Trapping

Murakami

Okazaki

Shiga

1989

Photochem & Photobiology

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An electron spin resonance (ESR) study on UV-photolysis of human and canine lens nuclei was carried out at room temperature. (1) At least two kinds of free radical signals, a narrow signal and a broad one, were detected at around g = 2.004. The latter is similar to that observed upon irradiation of a model solution containing both tryptophan and cysteine. (2) Two spin adducts were detected upon irradiation of canine lens in the presence of a spin trapping reagent (DMPO, 5,5-dimethyl-1-pyrroline N-oxide), i.e. a spin adduct of sulphur-centered radical (most likely glutathione thiyl radical) and the protonated adduct of solvated electron (presumably due to photo-ionization of tryptophan). (3) A tentative and simplified reaction mechanism of UV-induced damage is discussed on the basis of these observations.

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Application of Electron Spin Resonance Spectroscopy to Photochemistry

Wan

1974

Advances in Photochemistry

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Studies of the Triplet State of Proteins by Electron Spin Resonance Spectroscopy^*

Cited by 13 publications

References 26 publications

Indirect Photodegradation of Dissolved Free Amino Acids: The Contribution of Singlet Oxygen and the Differential Reactivity of DOM from Various Sources

Indirect Photodegradation of Dissolved Free Amino Acids: The Contribution of Singlet Oxygen and the Differential Reactivity of DOM from Various Sources

Near Uv‐induced Free Radicals in Ocular Lens, Studied by Esr and Spin Trapping

Application of Electron Spin Resonance Spectroscopy to Photochemistry

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Studies of the Triplet State of Proteins by Electron Spin Resonance Spectroscopy*

Cited by 13 publications

References 26 publications

Indirect Photodegradation of Dissolved Free Amino Acids: The Contribution of Singlet Oxygen and the Differential Reactivity of DOM from Various Sources

Indirect Photodegradation of Dissolved Free Amino Acids: The Contribution of Singlet Oxygen and the Differential Reactivity of DOM from Various Sources

Near Uv‐induced Free Radicals in Ocular Lens, Studied by Esr and Spin Trapping

Application of Electron Spin Resonance Spectroscopy to Photochemistry

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Product

Resources

About

Studies of the Triplet State of Proteins by Electron Spin Resonance Spectroscopy^*