Figure 1. Structural overview of ASMase.

(a) Domain organization of ASMase. SP, signal peptide; PL, proline-rich linker. (b) Closed and open ASMase coloured as in a. Consecutive grey spheres indicate the disordered linker between closed ASMase^sap and ASMase^cat in one molecule of the asymmetric unit. Boxed region magnified in c is not in the identical orientation. Glycans are omitted for clarity. Zincs are indicated as purple spheres. (c) ASMase active site. Zinc interactions are shown as dashes. Zinc–zinc distance=3.6 Å. Zinc–ligand distances range from 2.0 to 2.1 Å. Phosphate is coloured orange and red. Shown are zinc-interacting residues (beige) and residues important for leaving group protonation and substrate binding (green).