(S)-Aspartimide is a byproduct formed during solid-phase peptide synthesis (SPPS) of aspartic acid-containing peptides.1 Aspartimide is formed by cyclization of aspartic acid during Fmoc removal or peptide coupling.2
1.Ruczyński, J., Lewandowska, B., Mucha, P., et al.Problem of aspartimide formation in Fmoc-based solid-phase peptide synthesis using Dmab group to protect side chain of aspartic acidJ. Pept. Sci.14(3)335-341(2008) 2.Neumann, K., Farnung, J., Baldauf, S., et al.Prevention of aspartimide formation during peptide synthesis using cyanosulfurylides as carboxylic acid-protecting groupsNat. Commun.11(1)982(2020)