Glutathione and NADH, but not ascorbate, protect lens proteins from modification by UV filters | Macquarie University ResearchOnline

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Glutathione and NADH, but not ascorbate, protect lens proteins from modification by UV filters

Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.14/26423

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Title: Glutathione and NADH, but not ascorbate, protect lens proteins from modification by UV filters
Related: Experimental eye research, Vol. 74, Issue 4, p.503-511
DOI: 10.1006/exer.2001.1165
Publisher: Elsevier
Date: 2002
Author/Creator: Taylor, Lisa M
Author/Creator: Aquilina, J. Andrew
Author/Creator: Jamie, Joanne F
Author/Creator: Truscott, Roger J. W
Description: Age-dependent human lens colouration and fluorescence may stem primarily from the covalent binding of UV filters to crystallins. The tendency of the kynurenine (Kyn) UV filters to deaminate at neutral pH, with the generation of reactive α,β-ketoalkenes, underlies this phenomenon. In this study the authors examined the ability of small molecular weight antioxidants, which are known to be present in the lens, to inhibit this process. Crystallins were incubated with Kyn at pH 7 in the presence of glutathione (GSH), ascorbate or NADH. Ascorbate, even at high (15mΜ) levels, was not found to significantly retard the time-dependent covalent binding of Kyn to the proteins. GSH, and to a lesser extent NADH, however, had a major impact in preventing this modification. The increase in protein UV absorbance and fluorescence was inhibited by GSH intercepting the reactive ketone intermediate, to form a GSH–Kyn adduct. NADH seemed to protect by both reduction of the reactive ketone intermediate and by competing with Kyn for presumably hydrophobic sites on the crystallins. This may indicate that the covalent attachment of aromatic Kyn molecules could be facilitated by initial hydrophobic interactions. Since GSH is present at far greater concentrations than NADH, these results show that in primate lenses, GSH is the key agent responsible for protecting the crystallins from covalent modification.
Description: 9 page(s)
Subject Keyword: glutathione
Subject Keyword: ascorbate
Subject Keyword: NADH
Subject Keyword: kynurenine
Subject Keyword: lens
Subject Keyword: protein modification
Subject Keyword: ageing
Subject Keyword: cataract
Resource Type: journal article
Organisation: Macquarie University. Dept. of Chemistry and Biomolecular Sciences

Identifier: http://hdl.handle.net/1959.14/26423
Identifier: ISSN:1096-0007
Identifier: mq-rm-2002014985
Language: eng
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