Figure 3

Molecular modelling of king crab, salmon, and bovine trypsin. a – c: Electrostatic surfaces of (A) king crab trypsin (homology model), (B) bovine trypsin (pdb code: 1s0r), and (C) Atlantic salmon trypsin (pdb code: 1hj8). The most electropositive potential is shown in blue, whereas the most electronegative potential is shown in red. The PAR-2 agonist peptide is displayed in green ribbon. d: The N-terminal fragment of PAR-4 and PAR-2, Arg at the cleavage site (shaded), *: a conserved positive charged residue in tethered peptides. e and f: The location of 3 binding site residues in the king crab trypsin model that corresponds to different residues in the bovine and Atlantic salmon trypsin (shaded boxes in the structural alignment). Asp¹⁹⁶ in king crab trypsin corresponds to Met¹⁷⁵ in Atlantic salmon and Gln¹⁵⁵ in bovine trypsin; Arg²⁴⁴ in the king crab trypsin corresponds to Glu²²¹ in Atlantic salmon and Gln¹⁹⁹ in bovine trypsin; and Tyr²⁴⁷ in king crab trypsin corresponds to Asn²²⁴ in Atlantic salmon trypsin and to Lys²⁰² in bovine trypsin.