. 2012 Apr;40(4):642–647. doi: 10.1124/dmd.111.044081

TABLE 2.

Apparent kinetic parameters for the formation of 3MI metabolites by lung microsomes from WT, Cyp2a5-null, and Cyp2f2-null mice

Rates of metabolite formation were determined as described under Materials and Methods. Values presented are the means ± S.D. of data from three separate microsomal samples, each prepared from tissues pooled from five mice. Corresponding substrate-velocity curves are shown in supplemental material. The rates of HMI, I-3-C, and MOI formation were determined in the absence of added GSH. For HMI and GS-A2, the K_m and V_max values were estimated from relative rates determined in arbitrary units.

Metabolite	Strain	K_m	V_max	V_max/K_m
		μM	nmol · min⁻¹ · mg protein⁻¹	ml · min⁻¹ · mg⁻¹
I-3-C	WT	8.76 ± 1.30	0.050 ± 0.003	0.006
	Cyp2a5-null	8.12 ± 1.40	0.050 ± 0.002	0.006
	Cyp2f2-null	8.07 ± 0.26	0.015 ± 0.001^*	0.002
MOI	WT	32.7 ± 1.0	0.102 ± 0.003	0.003
	Cyp2a5-null	32.8 ± 1.0	0.105 ± 0.002	0.003
	Cyp2f2-null	62.8 ± 7.2^*	0.107 ± 0.006	0.002
GS-A1	WT	11.7 ± 2.6	0.459 ± 0.026	0.039
	Cyp2a5-null	11.6 ± 2.2	0.480 ± 0.010	0.042
	Cyp2f2-null	24.1 ± 4.3^*	0.112 ± 0.009^*	0.005
			Arbitrary units (analyte peak area · internal standard peak area⁻¹ · min⁻¹ · mg protein⁻¹)
HMI	WT	7.32 ± 1.3	107 ± 6
	Cyp2a5-null	7.10 ± 0.27	112 ± 7
	Cyp2f2-null	99.5 ± 4.8^*	14 ± 1^*
GS-A2	WT	6.55 ± 0.50	143 ± 5
	Cyp2a5-null	6.38 ± 0.61	147 ± 3
	Cyp2f2-null	71.7 ± 6.4^*	13 ± 1^*

P < 0.01, compared with WT mice (n = 3).