Use of 13C Labeling and NMR Spectroscopy for the Investigation of Degradation Pathways of Amadori Compounds

Advanced glycation end products (AGEs) are posttranslational modifications formed non-enzymatically from the reaction of carbohydrates and their degradation products with proteins. Accumulation of AGEs is associated with the progression of severe diabetic complications, for example, and elevated tissue levels of AGEs might even predict these pathologies. As AGE formation is often site-specific, mapping of these modification sites may reveal more sensitive and specific markers than the global tissue level. Here, 42 AGE modifications were identified in a bottom-up proteomic approach by tandem mass spectrometry, which corresponded to 36 sites in 22 high to medium abundant proteins in individual plasma samples obtained from type 2 diabetes mellitus (T2DM) patients with long disease duration (>10 years). Major modifications were glarg (11 modification sites) and carboxymethylation (5) of arginine and formylation (8), acetylation (7), and carboxymethylation (7) of lysine residues. Relative quantification of these sites in plasma samples obtained from normoglycemic individuals (n = 47) and patients with T2DM being newly diagnosed (n = 47) or of medium (2-5 years, n = 20) and long disease duration (>10 years, n = 20) did not reveal any significant differences.

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Site-specific analysis of advanced glycation end products in plasma proteins of type 2 diabetes mellitus patients

Greifenhagen

Frolov

Blüher

et al. 2016

Anal Bioanal Chem

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Oxidative degradation of N ε-fructosylamine-substituted peptides in heated aqueous systems

2015

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Glycation, or non-enzymatic glycosylation, is a common protein modification formed by reactions between reducing sugars (i.e. aldoses and ketoses) with protein amino groups. Resulting Amadori and Heyns compounds, respectively, can be oxidatively degraded yielding a structurally heterogeneous group of advanced glycation end-products. We have studied this process in aqueous conditions at 95 °C in terms of appearing products and their formation kinetics in the presence or absence of reactive oxygen species (ROS)-generating systems (iron(II) sulfate). RP-HPLC-ESI-MS revealed 20 products, 12 of which were confirmed after synthesis by identical retention times and fragmentation patterns. These products accumulated during the incubation period of 4 h (N(ε)-carboxymethyl-, N(ε)-formyl- and N(ε)-methyl lysine) or appeared intermediately (2-aminoadipic semialdehyde, N(ε)-ethanalyl lysine). Acidic and basic amino acid residues near the glycation site and elevated ROS levels in the reaction mixture had significant effects on both product formation and degradation kinetics.

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The pyridoxamine action on Amadori compounds: A reexamination of its scavenging capacity and chelating effect

Adrover¹,

Vilanova²,

Frau³

et al. 2008

Bioorganic & Medicinal Chemistry

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Use of 13C Labeling and NMR Spectroscopy for the Investigation of Degradation Pathways of Amadori Compounds

Cited by 5 publications

References 23 publications

Site-specific analysis of advanced glycation end products in plasma proteins of type 2 diabetes mellitus patients

Site-specific analysis of advanced glycation end products in plasma proteins of type 2 diabetes mellitus patients

Oxidative degradation of N ε-fructosylamine-substituted peptides in heated aqueous systems

The pyridoxamine action on Amadori compounds: A reexamination of its scavenging capacity and chelating effect

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