Table 1.

Observed rate constants for reactions of benzphetamine with Compounds I.^a

Enzyme	Bnz conc (mM)b	kobs (s−1)c
CYP2B4	0	4.4 ± 0.4
	0.075	20.8 ± 2.9
	0.15	34.1 ± 3.0
	0.225	37.5 ± 4.8
	0.30	40.9 ± 4.8
	0.45	44.3 ± 3.2
	0.60	42.6 ± 2.7
CYP2B4 E301Q	0	2.8 ± 0.2
	0.075	21.7 ± 2.9
	0.15	32.3 ± 3.2
	0.225	38.2 ± 2.7
	0.30	39.5 ± 2.0
	0.45	42.2 ± 3.0
	0.60	45.4 ± 3.4
CYP2B4 T302A	0	2.3 ± 0.2
	0.075	16.4 ± 3.5
	0.15	26.4 ± 3.0
	0.225	32.6 ± 4.5
	0.30	35.1 ± 4.0
	0.45	38.7 ± 3.8
	0.60	39.5 ± 2.9
CYP2B4 F429H	0	2.8 ± 0.2
	0.075	10.5 ± 1.5
	0.15	15.2 ± 1.9
	0.30	19.6 ± 3.2
	0.60	21.6 ± 2.8
CYP119	0	2.9 ± 0.3
	0.3	9.9 ± 1.3
	0.6	15.9 ± 2.0
	0.9	18.7 ± 1.0
	1.5	22.4 ± 1.3

^aReactions at 22 ± 1 °C in 50 mM phosphate buffer (pH 7.4).

^bConcentration of benzphetamine.

^cObserved rate constant with error at 1σ.