LC-MS Analysis of Markers for Advanced Glycation Endprocducts -Protein/Peptides Adducts

Advanced glycation end products (AGEs) are a heterogeneous group of proteins that have been modified with glucose or carbohydrates adducts, and are thought to be responsible for many complications of diabetes and aging. Free amino groups of proteins react slowly with reducing sugars such as glucose by the glycation or Maillard reaction, initially forming Schiff bases, which undergo rearrangement to form the relatively stable Amadori products. The Amadori products subsequently degrade into a-dicarbonyl compounds that react with amino groups of proteins to form cross-links, stable end products called advanced glycation end products (AGEs). AGEs have been shown to react (cross-link) with the amino group of the N-terminal amino acid residue and the side-chains of arginine and lysine residues. Therefore, glucose has been shown to be responsible, at least in part, for protein cross-linkage, oxidative stress and cytotoxicity. In this in vitro study model, the cross-linking of glucose (0.05, 0.5, 1.0 and 2.5 M) with bovine serum albumin incubated for different intervals of time (0, 7,14, 21, 28 and 35 days) was studied using LC-MS and Mascot database to search for the possible markers for glucose-peptides adducts. A total of twenty-seven peptides were matched in the database search query for control BSA out of which seven (m/z 922.69, 464.36, 582.41, 681.95, 834.49, 847.59 and 812.87) were found to be the possible markers for AGEs-protein/peptides adducts.