Mirror image proteins

Proteins composed entirely of unnatural D-amino acids and the achiral amino acid glycine are mirror image forms of their native L-protein counterparts. Recent advances in chemical protein synthesis afford unique and facile synthetic access to domain-sized mirror image D-proteins, enabling protein research to be conducted through 'the looking glass' and in a way previously unattainable, D-Proteins can facilitate structure determination of their native L-forms that are difficult to crystallize (racemic Xray crystallography); D-proteins can serve as the bait for library screening to ultimately yield pharmacologically superior D-peptide/D-protein therapeutics (mirror-image phage display); D-proteins can also be used as a powerful mechanistic tool for probing molecular events in biology. This review examines recent progress in the application of mirror image proteins to structural biology, drug discovery, and immunology.