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. All three compounds showed a resonance signal at 55.2 ppm in the 13C-NMR spectra as C1 methylene group of deoxyfructosyl, which represents direct evidence that they are Amadori compounds. All three compounds purified from GSSG/Glc or GSH/Glc mixtures also showed LC-MS/MS fragmentation patterns identical to those of the synthetically synthesized N-1-Deoxy-fructos-1-yl glutathione, N-1-Deoxy-fructos-1-yl GSSG and bis di-N, N'-1-Deoxy-fructos-1-yl GSSG. N-1-Deoxy-fructos-1-yl glutathione was shown to be a poor substrate for glutathione peroxidase (6.7% of the enzyme's original specific activity) and glutathione-S-transferase (25.7% of the original enzyme's specific activity). Glutathione reductase failed to recycle the disulfide bond within the structure of di-substituted bis di-N, N'-1-Deoxy-fructos-1-yl GSSG. It showed only 1% of the original enzyme's specific activity, but retained its ability to reduce the disulfide bond within the structure of N-1-Deoxy-fructos-1-yl GSSG by 57% of its original specific activity. Since the GSH concentration in diabetic lens is significantly decreased and the glucose concentration can increase 10-fold and higher, the formation of Amadori products of the different forms of glutathione with this monosaccharide may be favored under these conditions and could contribute to a lowering of glutathione levels and an increase of oxidative stress observed in diabetic lens.
Linetsky
Mikhail D
MD
Department of Ophthalmology, University of Missouri, Columbia, MO 65212, USA. linetskym@health.missouri.edu
Shipova
Ekaterina V
EV
Legrand
Roy D
RD
Argirov
Ognyan O
OO
D005632:Fructose / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D005947:Glucose / Q000737:chemistry / Q000378:metabolism*; D005978:Glutathione / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D019803:Glutathione Disulfide / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D005980:Glutathione Reductase / Q000737:chemistry; D006801:Humans; D013379:Substrate Specificity
C503574:N-1-deoxyfructos-1-yl glutathione; C503575:N-1-deoxyfructos-1-yl glutathione disulfide; C503576:bis di-N,N'-1-deoxyfructosyl glutathione disulfide; D005632:Fructose; D005980:Glutathione Reductase; D005978:Glutathione; D005947:Glucose; D019803:Glutathione Disulfide