Purchase this article with an account.
OK Argirov, V Chemoganskiy, BJ Ortwerth; A Novel Dehydroascorbate-lysine Advanced Glycation Endproduct is Markedly Altered by UVA Irradiation . Invest. Ophthalmol. Vis. Sci. 2002;43(13):847.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To model the damage of lysine residues in the eye lens proteins caused by the combined action of dehydroascorbic acid and UVA light. Methods: A compound corresponding to one of the major chromatographic peaks in the model reaction system dehydroascorbic acid - t-BOC-Lys was isolated and purified by preparative HPLC. The protective t-BOC group was eliminated using trifluoroacetic acid at 0 C, and the product was characterized by UV-, fluorescent-, 1H-NMR-, 13C-NMR-spectroscopy and mass-spectrometry. This compound was irradiated with UVA light in presence of a water-soluble human lens extract and the resulting mixture was analyzed by HPLC . Results: The spectral data suggest that the structure of the compound studied is: 1-(5-amino-5-carboxypentyl)-4-hydroxymethyl-3-pyridiniumolate. It exhibited a strong fluorescence at ex/em 286/398 nm and was partly stable during hydrolysis with 6N HCl for 21 h. A chromatographic peak corresponding to this compound was found in the HPLC profile of an acid hydrolyzate of in vitro ascorbilated calf lens proteins. The irradiation of this compound with UVA light in presence of a water-soluble human lens extract under argon resulted in its complete transformation to other products. The same result was obtained with a lens extract from which proteins were eliminated by filtration through 5000 Da cutoff filter, which indicates that low molecular weight compounds were involved in the phototransformation observed. Conclusion: We have isolated and determined the structure of a new glycation product of lysine and dehydroascorbic acid. This compound was extensively degraded by irradiation with UVA light in the presence of a water-soluble human lens extract. Our results suggest that measurements of the amounts of advanced glycation end products in the eye lens could underestimate the extent of glycation, because of subsequent structural alterations due to UVA light. The damage of lens proteins in vivo therefore could be a result from the combined action of glycation and UVA light.
This PDF is available to Subscribers Only