Table 1.

Classification system of Rieske non-heme oxygenases according to Batie et al. (1991)

Class	Number of components	Cofactor of the ferredoxin reductase	Iron–sulphur cluster in ferredoxin	Iron–sulphur cluster in oxygenase
IA	2	FMN [Fe2S2Cys4]	–	[Fe2S2Cys2His2] non-heme Fe2+
IB	2	FAD [Fe2S2Cys4]	–	[Fe2S2Cys2His2] non-heme Fe2+
IIA	3	FAD	[Fe2S2Cys4]	[Fe2S2Cys2His2] non-heme Fe2+
IIB	3	FAD	[Fe2S2Cys2His2]	[Fe2S2Cys2His2] non-heme Fe2+
III	3	FAD [Fe2S2Cys4]	[Fe2S2Cys2His2]	[Fe2S2Cys2His2] non-heme Fe2+