Photoreactions of human lens monomeric crystallins

Usha P. Andley; Barbara A. Clark

doi:10.1016/0167-4838(89)90199-4

Photoreactions of human lens monomeric crystallins

Usha P. Andley, Barbara A. Clark

Research output: Contribution to journal › Article › peer-review

11 Scopus citations

Abstract

Human lens β_s- and γ_A-crystallins exhibitvery similar tryptophan fluorescence emission maxima (329 nm). γ_A isolated from infant human lenses is photo-oxidized by 300 nm irradiation and forms water-insoluble aggregates; β_s or γ_A from young human lenses form a small amount of water-soluble crosslinked species. At least part of the mechanism of photodamage by 300 nm irradiation is photogeneration of the oxidant H₂O₂ via the generation of O₂^- radical, this reaction occurs via photosensitization by the tryptophan photo-oxidation product N-formylkynurenine (N-FK) or related species. These results indicate that even though the tryptophan residues of β_s- and γ_A-crystallins are in hydrophobic (buried) microenvironments as compared to those of the α- and β-crystallins, the photogeneration of N-FK is sufficient to produce O₂^- and H₂O₂.

Original language	English
Pages (from-to)	284-291
Number of pages	8
Journal	Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Volume	997
Issue number	3
DOIs	https://doi.org/10.1016/0167-4838(89)90199-4
State	Published - Aug 31 1989

Keywords

Cataract
Human lens
Hydrogen peroxide
N-Formylkynurenine
Oxidation
Photosensitizer
Superoxide
γ-Crystallin

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10.1016/0167-4838(89)90199-4

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title = "Photoreactions of human lens monomeric crystallins",

abstract = "Human lens βs- and γA-crystallins exhibitvery similar tryptophan fluorescence emission maxima (329 nm). γA isolated from infant human lenses is photo-oxidized by 300 nm irradiation and forms water-insoluble aggregates; βs or γA from young human lenses form a small amount of water-soluble crosslinked species. At least part of the mechanism of photodamage by 300 nm irradiation is photogeneration of the oxidant H2O2 via the generation of O2- radical, this reaction occurs via photosensitization by the tryptophan photo-oxidation product N-formylkynurenine (N-FK) or related species. These results indicate that even though the tryptophan residues of βs- and γA-crystallins are in hydrophobic (buried) microenvironments as compared to those of the α- and β-crystallins, the photogeneration of N-FK is sufficient to produce O2- and H2O2.",

keywords = "Cataract, Human lens, Hydrogen peroxide, N-Formylkynurenine, Oxidation, Photosensitizer, Superoxide, γ-Crystallin",

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doi = "10.1016/0167-4838(89)90199-4",

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T1 - Photoreactions of human lens monomeric crystallins

AU - Andley, Usha P.

AU - Clark, Barbara A.

PY - 1989/8/31

Y1 - 1989/8/31

N2 - Human lens βs- and γA-crystallins exhibitvery similar tryptophan fluorescence emission maxima (329 nm). γA isolated from infant human lenses is photo-oxidized by 300 nm irradiation and forms water-insoluble aggregates; βs or γA from young human lenses form a small amount of water-soluble crosslinked species. At least part of the mechanism of photodamage by 300 nm irradiation is photogeneration of the oxidant H2O2 via the generation of O2- radical, this reaction occurs via photosensitization by the tryptophan photo-oxidation product N-formylkynurenine (N-FK) or related species. These results indicate that even though the tryptophan residues of βs- and γA-crystallins are in hydrophobic (buried) microenvironments as compared to those of the α- and β-crystallins, the photogeneration of N-FK is sufficient to produce O2- and H2O2.

AB - Human lens βs- and γA-crystallins exhibitvery similar tryptophan fluorescence emission maxima (329 nm). γA isolated from infant human lenses is photo-oxidized by 300 nm irradiation and forms water-insoluble aggregates; βs or γA from young human lenses form a small amount of water-soluble crosslinked species. At least part of the mechanism of photodamage by 300 nm irradiation is photogeneration of the oxidant H2O2 via the generation of O2- radical, this reaction occurs via photosensitization by the tryptophan photo-oxidation product N-formylkynurenine (N-FK) or related species. These results indicate that even though the tryptophan residues of βs- and γA-crystallins are in hydrophobic (buried) microenvironments as compared to those of the α- and β-crystallins, the photogeneration of N-FK is sufficient to produce O2- and H2O2.

KW - Cataract

KW - Human lens

KW - Hydrogen peroxide

KW - N-Formylkynurenine

KW - Oxidation

KW - Photosensitizer

KW - Superoxide

KW - γ-Crystallin

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EP - 291

JO - Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular

JF - Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular

IS - 3

ER -

Photoreactions of human lens monomeric crystallins

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Keywords

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