Figure 1.

General mechanism of protein glycation. The process is initiated by a spontaneous nucleophilic addition reaction between the free amino group of a protein, generally belonging to N-terminal and lysine side chain, and the carbonyl group of a reducing sugar. This reaction rapidly forms a reversible Schiff base, which rearranges over a period of weeks to produce ketoamine or Amadori product. The Amadori product undergoes an irreversible cascade of reactions involving dehydration, hydrolysis, and rearrangements leading to the formation of advanced glycation end products (AGEs).