Antibody mimetics are organic compounds that, like antibodies, can specifically bind antigens, but that are not structurally related to antibodies. They are usually artificial peptides or proteins with a molar mass of about 3 to 20 kDa. (Antibodies are ~150 kDa.)
Nucleic acids and small molecules are sometimes considered antibody mimetics as well, but not artificial antibodies, antibody fragments and fusion proteins composed from these.
Common advantages over antibodies are better solubility, tissue penetration, stability towards heat and enzymes, and comparatively low production costs. Antibody mimetics are being developed as therapeutic and diagnostic agents.
Examples Antibody mimetic Scaffold Molar mass Example drug Affibody molecules Z domain of Protein A 6 kDa ABY-025 Affilins Gamma-B crystallin 20 kDa Ubiquitin 10 kDa SPVF 2801 Affimers (Adhirons) Cystatin 12–14 kDa Affitins Sac7d (from Sulfolobus acidocaldarius) 7 kDa Alphabodies Triple helix coiled coil 10 kDa CMPX-1023 Anticalins Lipocalins 20 kDa Avimers A domains of various membrane receptors 9–18 kDa DARPins Ankyrin repeat motif 10–19 kDa MP0112 Fynomers SH3 domain of Fyn 7 kDa GastrobodiesKunitz-type soybean trypsin inhibitor 20 kDa Kunitz domain peptides Kunitz domains of various protease inhibitors 6 kDa Ecallantide (Kalbitor) Monobodies 10th type III domain of fibronectin 10 kDa Pegdinetanib (Angiocept) nanoCLAMPs Carbohydrate Binding Module 32-2 (from Clostridium perfringens NagH) 16 kDa Optimers Flexible nucleic acid based scaffold; G-quadruplex 8-15 kDa Repebodiesleucine-rich repeatsPronectin™fourteenth fibronectin type-III scaffold of Human Fibronectin (14Fn3) 10 kDa Centyrinshighly stable fibronectin type III (FN3) domain 10 kDa Obodiesa high affinity binding protein domain engineered to bind to Hen Egg-white Lysozyme
See also Protein mimetic Optimer Ligand
References