Application of solid-phase extraction for the concentration of chromophores, fluorophores, and photosensitizers from lens protein digests.

Solid-phase extraction was applied for the separation of protein digests obtained from aged human lenses, cataractous human lenses, calf lens proteins in vitro glycated with dehydroascorbic acid and native calf lens proteins. Four fractions were collected after stepwise elution with different solvents. The first fraction contained about 80% of the digested material possessing free amino groups.

Influence of glutathione fructosylation on its properties.

Incubation of fructose and glutathione leads to the formation of N-2-deoxy-glucos-2-yl glutathione as the major glycation product, with characteristic positive ion at 470 Th in LC-MS spectra. Glutathione disulfide and fructose generate two compounds: N-2-deoxy-glucos-2-yl glutathione disulfide (m/z=775 Th) and bis di-N,N'-2-deoxy-glucos-2-yl glutathione disulfide (m/z=937 Th). N-2-deoxy-glucos-2-yl glutathione is 2.

K2P--a novel cross-link from human lens protein.

We report here the isolation of a novel acid-labile yellow chromophore from the enzymatic digest of human lens proteins and the identification of its chemical structure by LC-MS and NMR. This new chromophore exhibited a UV absorbance maximum at 343 nm and a molecular mass of 370 Da. One- and two-dimensional NMR analyses elucidated the structure as being 1-(5-amino-5-carboxypentyl)-4-(5-amino-5-carboxypentyl-amino)-3-hydroxy-2, 3-dihydropyridinium, a cross-link between the epsilon-amino groups of two lysine residues and a five-carbon atom ring.

Phototransformations of advanced glycation end products in the human eye lens due to ultraviolet A light irradiation.

Previous studies from this laboratory have shown that ultraviolet A (UVA) light can bleach the yellow advanced glycation end products (AGEs) of aged and cataractous human lenses. The AGEs OP-lysine and argpyrimidine are two UVA-absorbing posttranslational modifications that are abundant in the eye lens. The purpose of this study was to outline the changes in these two AGEs due to UVA irradiation.

Glucose-derived Amadori compounds of glutathione.

Under the chromatographic conditions used in these studies we observed time- and concentration-dependent formation of N-1-Deoxy-fructos-1-yl glutathione as the major glycation product formed in the mixtures of GSH with glucose. N-1-Deoxy-fructos-1-yl glutathione had a characteristic positively charged ion with m/z=470 Th in its LC-MS spectra. Mixtures of glutathione disulfide and glucose generated two compounds: N-1-Deoxy-fructos-1-yl GSSG (m/z=775 Th) as major adduct and bis di-N, N'-1-Deoxy-fructos-1-yl GSSG (m/z=937 Th) as the minor one.