Figure 4.

Structure-based sequence alignment of P₉-P₁ of the reactive loop (s4A) of α₁-antichymotrypsin (above) and the strand of the F-helix (hF) that inserts into the A-sheet in our structure (below). Complete (**) or partial (*) conservation of residues in the reactive loop and hF of α₁-antichymotrypsin are shown (conserved) as is the conservation of residues of hF throughout the serpin superfamily (consensus) (41).