Fig. 4
From: Repeated evolution of cytochrome P450-mediated spiroketal steroid biosynthesis in plants
The proposed catalytic sequence of CYP-mediated diosgenin biosynthesis from cholesterol. The on-pathway catalytic steps are colored in blue. The identity of the key intermediates were determined directly or inferred indirectly. Other possible mechanisms for the second cyclization step are presented in Supplementary Fig. 20
