Table 1

FMO content and kinetics of methimazole-dependent S-oxidation for expressed hFMO2.1 and mFMO2

	FMO Content		Kinetic Parameters ofS-Oxidation^1-a
	nmol FMO · mg⁻¹ Protein	Percent FMO2	V_max	K_m	V_max/K_m	R²
hFMO2.1
1	0.85	5.2	23.2	1.46	15.9	0.99
2	2.27	13.8	14.3	1.01	14.2	0.96
mFMO2
1	1.30	7.9	33.7	1.53	22.1	0.97
2	0.99	6.0	40.4	1.48	27.2	0.98

FMO content was determined by flavin assay (Fader and Siegel, 1973). The nanomoles of FAD · milligram⁻¹ associated with expressed control protein was subtracted from test proteins, and a 1 FAD/1 FMO molar ratio was assumed. Percent FMO2 was derived assuming 16.4 nmol of FAD · mg⁻¹ of hFMO2.1 and mFMO2.

↵1-a V_max = nanomoles · minute⁻¹ · nanomole⁻¹ of FMO;K_m = millimolar determined at pH 8.5 using methimazole at 0.2, 0.5, 1.0, 2.0, and 5.0 mM; R² = Lineweaver-Burke correlation coefficients.