Serpins are a superfamily of proteins with similar structures that were first identified for their protease inhibition activity and are found in all kingdoms of life.[1][2] The acronym serpin was originally coined because the first serpins to be identified act on chymotrypsin-like serine proteases (serine protease inhibitors).[3][4][5] They are notable for their unusual mechanism of action, in which they irreversibly inhibit their target protease by undergoing a large conformational change to disrupt the target's active site.[6][7] This contrasts with the more common competitive mechanism for protease inhibitors that bind to and block access to the protease active site.[8][9]
Protease inhibition by serpins controls an array of biological processes, including coagulation and inflammation, and consequently these proteins are the target of medical research.[10] Their unique conformational change also makes them of interest to the structural biology and protein folding research communities.[7][8] The conformational-change mechanism confers certain advantages, but it also has drawbacks: serpins are vulnerable to mutations that can result in serpinopathies such as protein misfolding and the formation of inactive long-chain polymers.[11][12] Serpin polymerisation not only reduces the amount of active inhibitor, but also leads to accumulation of the polymers, causing cell death and organ failure.[10]
^Carrell RW, Boswell DR (1986). "Serpins: the superfamily of plasma serine proteinase inhibitors". In Barrett AJ, Salvesen G (eds.). Proteinase Inhibitors. Research monographs in cell and tissue physiology. Vol. 12. Amsterdam: Elsevier Science Publishers BV. pp. 403–420. ISBN0-444-80763-2.