TABLE 5

Characteristics of CYP2B6 variants expressed in COS-1 cells^a

Variant	Apoprotein	K_m	V_max	V_max/K_m
	% CYP2B6.1	μM bupropion	pmol/mg/min	% CYP2B6.1
CYP2B6.1 wild type	100	65	215	100
CYP2B6.8 K139E	0	N.D.	N.D.	N.D.
CYP2B6.10 Q21L, R22C	120.3	72	192	80.6
CYP2B6.11 M46V	16.2	N.A.	∼4^b	∼2^b
CYP2B6.12 G99E	7.5	N.D.	N.D.	N.D.
CYP2B6.14 R140Q	82.5	117	48.7	12.5
CYP2B6.15 I391N	18.1	N.D.	N.D.	N.D.

N.D., not detectable after correction for background due to ∼4.4 ppm of contaminating product in bupropion substrate; N.A., not applicable due to linear relationship.
↵ a All values are means of two independent experiments.
↵ b At 1.6 mM substrate concentration.