Affitins consist of 66 amino acids and have a molecular mass of about 7 kDa, small compared to antibodies with some 130–150 kDa. Being obtained from a thermophile organism, they are unusually heat resistant proteins. Unlike antibodies, affitins are produced in vitro, and therefore can be generated more quickly. Due to their small size and high solubility, they can be easily produced in large amounts using bacterial expression systems.
^Pacheco, S; Béhar, G; Maillasson, M; Mouratou, B; Pecorari, F (2014). "Affinity transfer to the archaeal extremophilic Sac7d protein by insertion of a CDR". Protein Engineering Design and Selection27 (10): 431–8. doi:10.1093/protein/gzu042. PMID25301962.edit
^Krehenbrink, M; Chami, M; Guilvout, I; Alzari, PM; Pécorari, F; Pugsley, AP (2008). "Artificial binding proteins (Affitins) as probes for conformational changes in secretin PulD". Journal of Molecular Biology383 (5): 1058–68. doi:10.1016/j.jmb.2008.09.016. PMID18822295.