 [3]

In proteins aspartate sidechains are often hydrogen bonded to form asx turns or asx motifs, which frequently occur at the N-termini of alpha helices.The L-isomer of Asp is one of the 22 proteinogenic amino acids, i.e., the building blocks of proteins.Aspartic acid, like glutamic acid, is classified as an acidic amino acid, with a pKa of 3.9, however in a peptide this is highly dependent on the local environment, and could be as high as 14.