R-Aspartimide ((R)-3-aminopyrrolidine-2,5-dione) is the cyclic amine formed by the dehydration of the amino acid, D-asparagine. The formation of aspartimides is a common synthetic by-product of peptide chemistry in aspartic acids there is little in the literature describing the occurrence and role of this cyclic metabolite. Despite R-aspartimide’s close relationship to the proteogenic amino acids its biological role is largely unexplored.