Superimposition of MaPgb*(III) structures in complex with different ligands.
(A) Superimposition of homodimeric ligand-free MaPgb*(III) (magenta) onto MaPgb*(III)-cyanide (yellow), MaPgb*(III)-azide (green), MaPgb*(III)-imidazole (orange), MaPgb*(III)-nicotinamide (brown), and MaPgb*(II)-O2 (cyan). The subunit-subunit interface is indicated and relevant helices labeled. Red circles highlight the position of the 149–154 region in both subunits. (B) The 149–154 region in one MaPgb* subunit. For clarity only the side chains of Ile(149)G11, Thr(150)G12, Thr(152)G14, and Met(153)G15 from the ligand-free MaPgb*(III) (magenta) and MaPgb*(III)-cyanide (yellow) structures are compared, as representative of the two haem distal site open and closed conformations, respectively. The corresponding different orientations of the Trp(60)B9 side chain are also shown. The maximum Cα-backbone displacement at Ala(151)G13 is highlighted by a black dotted circle. For clarity, the side chain and label of Ala(151)G13 are omitted.