Table 3

Kinetic constants for human FMO1 MBP, FMO3 MBP, and variants of human FMO3 MBP3-a

EnzymenKmkcat3-bkcat/KmSubstrate
Human FMO168.0  ± 2.44.0  ± 1.60.55-DPT3-c
Human FMO3
 (WT) Glu-1583154.9  ± 31.850.7  ± 1.60.335-DPT
 Lys-1583187.5  ± 34.144.4  ± 17.70.235-DPT
 Met-257382.3  ± 41.713.2  ± 4.60.165-DPT
 510X461.6  ± 12.90.09  ± 0.090.0015-DPT
Human FMO14486  ± 34.825.9  ± 3.70.05TMA3-d
Human FMO3
 (WT) Glu-158432.3  ± 7.1189  ± 215.85TMA
 Lys-1584206  ± 21105  ± 3.80.51TMA
 Met-25741151  ± 10728.2  ± 5.10.02TMA
 510X41034  ± 13934.9  ± 14.60.03TMA
Human FMO1N.D.3-e Tyramine
Human FMO3
 (WT) Glu-1584231  ± 43.4110  ± 16.10.48Tyramine
 Lys-1584941  ± 103106.1  ± 4.60.11Tyramine
 Met-25742164  ± 8741.3  ± 6.80.02Tyramine
 510X41384  ± 11011.4  ± 6.90.008Tyramine
  • 3-a Product determined by HPLC or radiometric assay as described in Materials and Methods. n = number of determinations ± S.D.

  • 3-b kcat is given in nmol · min−1 · nmol−1 of protein, with nanomoles of protein determined on the basis of FAD content as described in Materials and Methods.

  • 3-c Limit of detection, 20 pmol · min−1 · mg−1 of protein.

  • 3-d Limit of detection, 4 pmol · min−1 · mg−1 of protein.

  • 3-e Not detectable; limit of detection, trans oxime, 20 pmol · min−1 · mg−1 of protein.