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Updated: Aug 12, 2026
Characterization of Molecular Mechanisms of In vivo UVR Induced Cataract
Published on: November 28, 2012
The damaging effect of UV-C irradiation on lens alpha-crystallin
Noriko Fujii1, Hiroki Uchida, Takeshi Saito
1Research Reactor Institute, Kyoto University, Sennan, Osaka, Japan. nfujii@hl.rri.kyoto-u.ac.jp
Purpose:
To evaluate the effect of UV-C irradiation on the structural properties of alpha-crystallin and its chaperone activity.
Methods:
alpha- and betaL-crystallins were isolated from bovine lenses using gel chromatography. The purified alpha-crystallin was subjected to UV-C irradiation (254 nm; 1, 2, 5, 10, 20, 50 J/cm2). We measured the tryptophan fluorescence, circular dichroism (CD) spectroscopy in the far UV, and the chaperone activity of both irradiated and non-irradiated alpha-crystallin.
Results:
The tryptophan fluorescence of alpha-crystallin decreased, whereas the N-formylkynurenine fluorescence increased markedly with increasing doses of UV-C irradiation. Both the oxidation of Met1 and the racemization of Asp151 of alphaA-crystallin increased at a dose of 1-2 J/cm2 and then gradually decreased. The CD spectrum showed that the secondary structure of alpha-crystallin altered with increasing radiation dose, and almost all of the beta-sheet structure was lost at doses above 50 J/cm2. The chaperone activity of alpha-crystallin irradiated with doses under 5 J/cm2 remained intact. However, it was reduced to only 40% after irradiation at 10 J/cm2.
Conclusions:
Our study suggests that photo-oxidation of tryptophan residues in alpha-crystallin may be one of the events that affects the three-dimensional packing array and chaperone activity of this lens protein.
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