Fig. 4. (a) Superimposed image of HasA-bound haem (white) and HasA with Co-Ph₄Pc (purple). (b)–(d) Superimpositions of the crystal structures of holo-HasA (white) and HasA with Co-Ph₄Pc (conformation-A (cyan) and B (orange)). (b) The side chain of Arg129 was flipped to accommodate the 9-phenyl of CoPh₄Pc. The side chain of Arg129 is shown as spheres. (c) The 9-phenyl was extruded towards the outside of HasA in conformation-B to avoid steric repulsion with Arg129. (d) Conformational change of HasA-loops around haem-binding site. CoPh₄Pcs of both conformations are shown as grey sphere.