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Proceedings Paper

Photosensitized Oxidation Of Lens Crystallins: Role Of Conformational Changes In Cataract
Author(s): Usha Andley; Barbara Clark; Leo T. Chylack Jr.
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Paper Abstract

Photooxidation of lens crystallins has been found to induce significant changes in their tertiary structures, and is likely to play an important role in the crosslinking and aggregation of these proteins observed in aged and cataractous human lenses. Irradiation of calf lens α-, β- and γ- crystallins in the presence of visible light and the photosensitizers methylene blue or riboflavin and by irradiation with 300 nm radiation has been investigated. Of the three classes of crystallins, only the monomeric γ-crystallins have been found to undergo partial insolubilization in photosensitized reactions. The insoluble material is highly crosslinked by nondisulfide linkages. Moreover, change in the molecular charge of the protein is observed. Analysis of the soluble fraction of the irradiated γ-crystallin, by circular dichroism and fluorescence spectroscopy, reveals changes in the tertiary structure of the protein, probably involving a partial unfolding of the molecule. Active species of molecular oxygen play a role in these structural modifications. The change in conformation is different for each photosensitizer used, suggesting that the sensitizer-protein complexation may be important.

Paper Details

Date Published: 19 February 1988
PDF: 6 pages
Proc. SPIE 0847, New Directions in Photodynamic Therapy, (19 February 1988); doi: 10.1117/12.942710
Show Author Affiliations
Usha Andley, Harvard Medical School (United States)
Barbara Clark, Harvard Medical School (United States)
Leo T. Chylack Jr., Harvard Medical School (United States)

Published in SPIE Proceedings Vol. 0847:
New Directions in Photodynamic Therapy
Douglas C. Neckers, Editor(s)

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