Figure 5. Stereo views of structural models for WT and elafin mutants complexed to HNE and PPE.

(A) and (B) Molecular representations of WT elafin–enzyme complex (white) superimposed on to an elafin^M25K–enzyme complex (grey). The WT Met²⁵ residue is yellow and Lys²⁵ blue. Residues making direct contact with residue 25 from the inhibitor are in stick representation. Protein backbones are in ribbon representation. Magenta and black dashed lines represent hydrogen bonds for the complex containing pre-elafin and pre-elafin^M25K respectively. (A) Inhibitors complexed to PPE. The yellow dashed line represents the distance between Lys²⁵i side chain nitrogen atom and Arg⁶¹e ζ carbon. (B) Inhibitors complexed to HNE. (C) Elafin^M25G complexed to PPE. The yellow mesh represents the cavity left by the replacement of Met²⁵ by Gly²⁵.