“…Succinimide intermediates can also be formed from asparagine (Asn) residues (this is irreversible because of the release of an ammonia molecule) [1,2,10,11,12,13,14]; therefore, in proteins and peptides, there can be d -Asp and d -β-Asp residues originating from l -Asn residues. The formation of the biologically uncommon l -β-Asp, d -Asp, and d -β-Asp residues have been paid considerable attention due to the relevance to aging and pathologies, especially those of age-related diseases such as cataract and Alzheimer’s disease [5,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42]. …”