Recognition of Class II MHC Peptide Ligands That Contain β-Amino Acids

Proteins are composed of α-amino acid residues. This consistency in backbone structure likely serves an important role in the display of an enormous diversity of peptides by class II MHC (MHC-II) products, which make contacts with main chain atoms of their peptide cargo. Peptides that contain residues with an extra carbon in the backbone (derived from β-amino acids) have biological properties that differ starkly from those of their conventional...