Fig. 2. Models of serpin structure. (A) Position of nec mutations mapped onto the scaffold of monomeric ₁-antitrypsin (Elliott et al., 2000). The GluLys substitution found in Z-₁-antitrypsin, nec⁹ and nec²⁰, maps at the hinge region between the reactive center loop (red) and ß-sheet A (green). ß-sheet B is colored yellow and -helix A is blue. Nec^S>F carries the Ser¹³¹Phe substitution homologous to that of ₁-antitrypsin-Siiyama, Ser⁵³Phe. (B) Loop-sheet polymer of Z-₁-antitrypsin and Nec⁹.