Deamidation of Asparagine in Peptides and Proteins

The deamidation of asparagine with the associated formation of isoaspartic acid ^1,2 and peptide bond cleavage ³ is one the most common causes of heterogeneity in biopharmaceutical protein products. The process of deamidation of asparagine involves the formation of a cyclic succinimide which decomposes to form aspartic acid or isoaspartic acid. Deamidation results in heterogeneity of the protein, which can result in a loss of potency. ^4,5 Factors that affect deamidation of asparagine residues include the amino acid sequence around the asparagine residue, pH, buffer composition and temperature. In general, asparagine in proteins is less susceptible to deamidation than peptides. ⁶ Glutamine is also susceptible to deamidation. ⁷ Selected studies of deamidation of peptides and proteins are shown below.