ser·​pin | \ˈsir-pən, ˈser- \

Medical Definition of serpin 

: any of a group of structurally related proteins (as antithrombin and antitrypsin) that are typically inhibitors of proteases having serine as the main funtional group and that include some (as ovalbumin and angiotensinogen) which have lost their inhibitory action The identification of an intracellular serpin (protease inhibitor) that prevents necrosis caused by multiple noxious stimuli indicates that necrosis can be regulated, programmed, and driven by a peptidase stress-response pathway. — Richard S. Hotchkiss, M.D. et al., The New England Journal of Medicine, 15 Oct. 2009 Apparently evolution has completely adapted the serpin structure for its new role in these proteins as a transport agent, as there is no evidence of any retained protease inhibitory activity. — Daniel F. Voytas, et al., letter in Nature, 17 Nov. 1988

History and Etymology for serpin

serine proteinase inhibitor

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