Table 4

Catalytic activities and Michaelis-Menten parameters of CYPs from human liver microsomes and various expression systems

CYP: Marker Reaction	Reaction Conditions		V_max	K_m	K_m (human liver microsomes)^a
	Time	CYP
	[linearity range]
	min	pmols	nmol/min/nmol CYP	μM	μM
1A1
1-EthoxyresorufinO-deethylation	10 [5–20]	3 [0.5–5]	1.5	0.134
1A2
7-Ethoxyresorufin O-deethylation	10 [5–15]	12.5 [2.5–12.5]	0.9	1.05	0.19–2.0
2C8
6α-Paclitaxel hydroxylation	30 [20–50]	25 [10–80]	1.14	4.9	4–15
2C9
Diclofenac 4-hydroxylation	10 [5–20]	10 [5–20]	15.0	8.3	2.9–22
2C19
S-Mephenytoin 4-hydroxylation	45 [15–45]	50 [10–50]	2.14	54	16–80
2D6
Bufuralol 1′-hydroxylation	10 [5–15]	3 [0.2–3.2]	8	15	8–44
2E1
Chlorzoxazone 6-hydroxylation	30 [25–60]	50 [25–100]	2.8	177	22–49
3A4
Testosterone 6β-hydroxylation	20 [5–20]	30 [5–30]	8	55	53–229
3A5
Testosterone 6β-hydroxylation	30 [5–30]	30 [5–30]	1.8	84

^a Values obtained from the following literature: Ono et al., 1995; Peter et al., 1990; Leemam et al., 1993;Iwata et al., 1998; Yamazaki et al., 1998; Boobis et al., 1998; Carlile et al., 1998; Kronbach et al., 1987; Rahman et al., 1994.