Before revision: It is formed via a chemical reaction in which the nitrogen atom of the following peptide group (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 symmetric succinimide intermediate (in red).
After revision: It is formed via 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 symmetric succinimide intermediate (in red).