Vitamin C induced oxidation of eye lens gamma crystallins

Atalay, Arzu; Öğüş, Ay; Bateman, O.A.; Slingsby, C.

doi:10.1016/s0300-9084(98)80068-0

Cited by 15 publications

(14 citation statements)

References 23 publications

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“…9−12 Several modifications that reduce protein stability and promote aggregation are more abundant in cataractous lenses than healthy lenses. 10,13,14 Although a number of factors are known to increase covalent modification and the risk of cataract, one ubiquitous hazard is solar ultraviolet radiation.…”

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confidence: 99%

Tyrosine/Cysteine Cluster Sensitizing Human γD-Crystallin to Ultraviolet Radiation-Induced Photoaggregation in Vitro

et al. 2014

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Ultraviolet radiation (UVR) exposure is a major risk factor for age-related cataract, a protein-aggregation disease of the human lens often involving the major proteins of the lens, the crystallins. γD-Crystallin (HγD-Crys) is abundant in the nucleus of the human lens, and its folding and aggregation have been extensively studied. Previous work showed that HγD-Crys photoaggregates in vitro upon exposure to UVA/UVB light and that its conserved tryptophans are not required for aggregation. Surprisingly, the tryptophan residues play a photoprotective role because of a distinctive energy-transfer mechanism. HγD-Crys also contains 14 tyrosine residues, 12 of which are organized as six pairs. We investigated the role of the tyrosines of HγD-Crys by replacing pairs with alanines and monitoring photoaggregation using light scattering and SDS-PAGE. Mutating both tyrosines in the Y16/Y28 pair to alanine slowed the formation of light-scattering aggregates. Further mutant studies implicated Y16 as important for photoaggregation. Mass spectrometry revealed that C18, in contact with Y16, is heavily oxidized during UVR exposure. Analysis of multiple mutant proteins by mass spectrometry suggested that Y16 and C18 likely participate in the same photochemical process. The data suggest an initial photoaggregation pathway for HγD-Crys in which excited-state Y16 interacts with C18, initiating radical polymerization.

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confidence: 99%

Tyrosine/Cysteine Cluster Sensitizing Human γD-Crystallin to Ultraviolet Radiation-Induced Photoaggregation in Vitro

et al. 2014

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“…Our present findings corroborate previous results. 34,35 The decrease could have been due to increased utilization of vitamin C and vitamin E as an antioxidant defense against increased reactive oxygen species or to a decrease in GSH level, since GSH is required for the recycling of vitamin C, 36 and vitamin C is required for the regeneration of vitamin E. Administration of P. betle increased the levels of vitamin C and vitamin E in ethanol-treated rats. P. betle is known for its antioxidant properties, which may be due to the presence of phenol, particularly hydroxy chavicol (4-allyl pyrocatechol), carotenoids (as vitamin A), and vitamin C. 37 Clinical complications in oxidative stress-related disease might be due to the dysfunction of key antioxidant enzymes.…”

Section: Discussionmentioning

confidence: 99%

Influence of Piper betle on Hepatic Marker Enzymes and Tissue Antioxidant Status in Ethanol-Treated Wistar Rats

Saravanan

Prakasam

Ramesh

et al. 2002

Journal of Medicinal Food

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Piper betle L. is a commonly used masticatory in Asia. This study was carried out to investigate the hepatoprotective and antioxidant properties of P. betle, using ethanol intoxication as a model of hepatotoxic and oxidative damage. Ethanol-treated rats exhibited elevation of hepatic marker enzymes and disturbances in antioxidant defense when compared with normal rats. Oral administration of P. betle extract (100, 200, or 300 mg/kg body weight) for 30 days significantly (P <.05) decreased aspartate aminotransferase (AST), alanine aminotransferase (ALT), thiobarbituric acid reactive substances (TBARS), and lipid hydroperoxides in ethanol treated rats. The extract also improved the tissue antioxidant status by increasing the levels of nonenzymatic antioxidants (reduced glutathione, vitamin C, and vitamin E) and the activities of free radical-detoxifying enzymes such as superoxide dismutase, catalase, and glutathione peroxidase in liver and kidney of ethanol-treated rats. The highest dose of P. betle extract (300 mg/kg body weight) was most effective. The results were comparable with the known hepatoprotective drug, silymarin. These results indicate that P. betle could afford a significant hepatoprotective and antioxidant effect.

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“…2(B)]. This protein contains six free cysteines per molecule, four that are common with gB-crystallin (Atalay et al, 1998), and would also be expected to readily form mixed disul®des with GSH. It is not clear, however, whether crosslinked dimers of g-crystallins were formed in the HBO-treated lenses.…”

Section: Discussionmentioning

confidence: 99%

“…It is not clear, however, whether crosslinked dimers of g-crystallins were formed in the HBO-treated lenses. Such dimers for gB-and gS-crystallins have been shown to be induced under oxidative conditions (Atalay et al, 1998;Pande et al, 1995); however, the cited studies were conducted using puri®ed proteins in the absence of GSH. Disul®de bonding has been identi®ed as a major post-translational modi®cation of gS-, gD-and gC-crystallins in the aging human lens (Hanson, Smith and Smith, 1998).…”

Section: Discussionmentioning

confidence: 99%

The Effects of Hyperbaric Oxygen on the Crystallins of Cultured Rabbit Lenses: a Possible Catalytic Role for Copper

Padgaonkar

Leverenz

Fowler

et al. 2000

Experimental Eye Research

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Vitamin C induced oxidation of eye lens gamma crystallins

Cited by 15 publications

References 23 publications

Tyrosine/Cysteine Cluster Sensitizing Human γD-Crystallin to Ultraviolet Radiation-Induced Photoaggregation in Vitro

Tyrosine/Cysteine Cluster Sensitizing Human γD-Crystallin to Ultraviolet Radiation-Induced Photoaggregation in Vitro

Influence of Piper betle on Hepatic Marker Enzymes and Tissue Antioxidant Status in Ethanol-Treated Wistar Rats

The Effects of Hyperbaric Oxygen on the Crystallins of Cultured Rabbit Lenses: a Possible Catalytic Role for Copper

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