Photosensitized Oxidation Of Lens Crystallins: Role Of Conformational Changes In Cataract

Usha Andley; Barbara Clark; Leo T. Chylack Jr.

doi:10.1117/12.942710

19 February 1988 Photosensitized Oxidation Of Lens Crystallins: Role Of Conformational Changes In Cataract

Usha Andley, Barbara Clark, Leo T. Chylack Jr.

Proceedings Volume 0847, New Directions in Photodynamic Therapy; (1988) https://doi.org/10.1117/12.942710
Event: Cambridge Symposium on Optics in Medicine and Visual Image Processing, 1987, San Diego, CA, United States

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.

Citation Download Citation

Usha Andley, Barbara Clark, and Leo T. Chylack Jr. "Photosensitized Oxidation Of Lens Crystallins: Role Of Conformational Changes In Cataract", Proc. SPIE 0847, New Directions in Photodynamic Therapy, (19 February 1988); https://doi.org/10.1117/12.942710

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