TABLE 1

K_m and V_max values for the P450-catalyzed reactions with human liver microsomes and Supersomes and calculated RAFs

P450 Isoform-Substrate (Reported K_m Values)	Human Liver Microsomes			Supersomes		RAF^a
P450 Isoform-Substrate (Reported K_m Values)		K_m	V_max ^b	K_m	V_max ^b	RAF^a
	μM		μM
CYP1A2-Phenacetin (30 μM)	20.0	1.79	15.8	2.25	0.63
CYP2C9-Tolbutamide (400 μM)	317	0.10	113	0.04	0.75
CYP2C19-S-Mephenytoin (60 μM)	32.4	0.05	33.5	0.13	0.41
CYP2D6-Dextromethorphan (5 μM)	6.56	2.02	2.50	3.82	0.20
CYP3A4-Testosterone (47 μM)	46.6	1.64	28.5	1.74	0.58

↵ a RAF = (V_max/K_m of CYPn in HLM/V_max/K_m of cDNA-expressed CYPn)
↵ b V_max values are represented as peak area ratio of amount of metabolite formed/internal standard.