Table 2.

Apparent catalytic parameters of the FAD-dependent enzymes PbfC, PbfD1, and PbfD2

Enzyme	Substrate	kcat/KM (M−1 s−1)	kcat (s−1)	KM (mM)
PbfC	M1AEP	45000 ± 2700	9.0 ± 0.2	0.20 ± 0.01
	AEP	110 ± 6	2.2 ± 0.1	20 ± 1.7
PbfD1	M1AEP	2300 ± 160	13.2 ± 0.54	5.8 ± 0.62
	AEP	130 ± 6	9.1 ± 1.7	71 ± 16
	M2AEP	400 ± 26	22 ± 4.5	54 ± 14
PbfD2	M1AEP	13500 ± 550	4.9 ± 0.07	0.36 ± 0.02
	AEP	3400 ± 320	8.9 ± 0.3	2.6 ± 0.32

The kinetic parameters were obtained by fitting the titration data reported in Figure 4 (panels G-I) to the Michaelis-Menten equation. The reported parameters (± SE of the fitting) are rounded to the first two significant figures; they are deemed ‘apparent’ because they were measured in the presence of a fixed concentration of the electron acceptor co-substrate. The activity of PbfC was assessed in the presence of 80 μM DCPIP and 3 mM PMS. Activities of the PbfD enzymes were determined in aerated solutions, i.e., in the presence of ∼0.25 mM O₂. Related to Figure S8.