Table 2.

Reduction of CYP109B1 Fe³⁺-heme by different redox partners.

Reconstituted systema	Heme-iron reduction rateb
	k 1 (s−1)	k 2 (s−1)
Fpr / FldA / CYP109B1 – [4:4:1]	0.004 ± 0.001	0.027 ± 0.008
Fpr / YkuN / CYP109B1 – [4:4:1]	0.009 ± 0.001	0.078 ± 0.023
YR / CYP109B1 – [4:1]	0.002 ± 0.001	0.030 ± 0.002
YR-P5 / CYP109B1 – [4:1]	0.008 ± 0.002	0.045 ± 0.005
YR-G5 / CYP109B1 – [4:1]	0.007 ± 0.001	0.035 ± 0.002

^aValues in brackets indicate applied ratio as well as final concentration (µM) of the proteins in the employed reconstituted systems. ^bThe heme-iron reduction rates were measured as described in the Methods section. Kinetic traces were fit to a bi-exponential function, revealing a slow and a fast phase. Typical kinetic traces and corresponding fits are shown in the online Supplementary Information. Presented reduction rates represent average values of at least three independent reactions carried out under anaerobic conditions at 20 °C.