Fig. 5
a Purification of rSmCA by immobilized metal affinity chromatography (IMAC). Lane 1 shows purified rSmCA after resolution by SDS-PAGE and stained with Coomassie Blue. The arrow shows rSmCA. M represents molecular size markers (kDa). Anti-SmCA antibodies detect rSmCA (lane 3), and native SmCA in an adult schistosome extract (lane 4, arrow), by western blot analysis. b–d Crystal structure of rSmCA. Ribbon diagram of the SmCA monomer structure (b) along with depiction of the enzyme active site in a space fill and stick model (c) with the zinc ion (gray sphere), its ligands (His117, His119, and His142, indicated) and water molecules (red spheres). A Fo–Fc difference Fourier omit map is also shown contoured at 2 σ. Panel d represents superposition of a monomer of SmCA (tan) with the two hCAs II mutants (PDB 4PXX, pink and PDB 4HBA, light blue, whose sequences are given in supplementary fig. 4). The catalytic zinc ion is represented as a gray sphere
