Fig. 2: Haem active site structures of P450BM3 F393H and F87A/F393H.

The oxidised (A, B), reduced (C, D), and oxygen-bound (E, F) forms of F393H (A, C, E) and F87A/F393H (B, D, F) are depicted. Haem, Cys400, Thr268, C7ProPhe, styrene, O2, and the side chains of Phe87, Ala87, and His393 are shown as stick models. Styrene is highlighted in orange. Water molecules close to haem are depicted as small spheres. Hydrogen bonds are represented as red dotted lines. The inset in each panel shows the polder omit map of styrene represented as a mesh contoured at 3.0σ (A–D) and 4.0σ (E, F). The resolutions of the XFEL data are 1.80 Å (F393H) and 1.85 Å (F87A/F393H) for the oxidised form, 1.60 Å (F393H and F87A/F393H) for the reduced form, and 1.50 Å (F393H and F87A/F393H) for the oxygen-bound form.