The X-ray crystal structure of murine α₂-antiplasmin_Δ43. (A) Cartoon representation of α₂-antiplasmin_Δ43, with the A-sheet in red, the B-sheet in green, and the C-sheet in yellow, the RCL in magenta (missing residues in dotted line), the 9 helices (labeled) and loops in gray. The C-terminal region is in blue. The N and C termini are labeled. (B) Superposition of α₂-antiplasmin_Δ43 (cyan) and the antitrypsin/trypsin Michaelis complex (1OPH)²¹  yellow and pink, the RCL of α₂-antiplasmin_Δ43 in green and C-terminal extension in blue, P7-P10 of antitrypsin circled. Figures are produced with PyMOL (Delano Scientific, Palo Alto, CA). (C) A close-up view of molecular contacts between the C-terminal region and the serpin molecule. A total of 10 hydrogen bonds (magenta dashed lines; 3 of which are water mediated) are made between the C-terminus and the body of the serpin. Water molecules are cyan spheres. Colouring scheme for the residues are as in panel A, and they are labeled with the single letter code.