Photoreactions of human lens monomeric crystallins

Usha P. Andley, Barbara A. Clark

Research output: Contribution to journalArticle

9 Scopus citations

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.

Original languageEnglish
Pages (from-to)284-291
Number of pages8
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Volume997
Issue number3
DOIs
StatePublished - Aug 31 1989
Externally publishedYes

Keywords

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

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