Serpin K

Serpins are protease inhibitors that promote both inhibition and clearance of target proteases. Serpins form exceptionally tight interactions with their target protease. Nevertheless, they are suicide substrate inhibitors, and are found cleaved and inactivated on release from protease. Serpins exhibit conformational polymorphism. Residues known to interact with protease are found either on the surface and accessible in the active form, or buried and inserted as the central strand of the largest b-sheet (sheet A). The insertion of the strand (s4A) into sheet A can occur spontaneously, but for most serpins it occurs only on cleavage and inactivation. Partial or full formation of s4A may occur in the protease-serpin complexes.

The structure of active Serpin 1K from Manduca sexta and a model for serpin-protease complex formation.

Jinping Li, Zhulun Wang, Bertram J Canagarajah, Haobo Jiang, Michael Kanost and Elizabeth Goldsmith.