 Such a change is caused by a chemical reaction in which the nitrogen atom on the N+1 following peptide bond (in black at top right of Figure 1) nucleophilically attacks the γ-carbon of the side chain of an asparagine or aspartic acid residue, forming a succinimide intermediate (in red).Hydrolysis of the intermediate results in two products, either aspartic acid (in black at left) or isoaspartic acid, which is a β-amino acid (in green at bottom right).The reaction also results in the deamidation of the asparagine residue.