Table 3

Comparison of turnover number and Km values determined in our laboratory with literature values for the five major human hepatic CYPs

IsoformCYP SourceAstra CharnwoodLiteratureReferences
TNKmTNKm
min−1 μm min−1 μm
HLM20  ± 33-a 0.5  ± 01–14003-a 0.2–0.5 Clarke et al., 1994; Pastrakuljic et al., 1997; Williams et al., 1986
CYP1A2B-lymphoblasts0.4  ± 0.10.5  ± 0.3
E. coli membranes0.6  ± 0.21.0  ± 0.3
Other0.7–2.50.01–1.7 Fisher et al., 1992; Eugster et al., 1993; Sandhu et al., 1993; Iwata et al., 1998
HLM350, 6003-a 400, 2000538–41003-a 92–160 Miners et al., 1996; Tracy et al., 1997; Rodrigues et al., 1996
CYP2C9B-lymphoblasts4.9 116 11, 41430, 341 Tracy et al., 1997; Rodrigues et al., 1996
E. coli membranes6.7  ± 0.9307  ± 65
HLM350, 140003-a 100, 1500(2673-b, 1400, 2120)3-a 203-b, 184, 557 Yasumori et al., 1993; Andersson et al., 1994; Zomorodi and Houston, 1996
Baculosomes1.0  ± 0.217  ± 2
CYP2C19B-lymphoblasts − b50.23  ± 0.0851, 69
B-lymphoblasts + b51.6
E. coli membranes3-c 0.1
E. colimembranes3-d 3.7  ± 0.331  ± 3
Other1.8, 2.321, 32 Jung et al., 1997; Ono et al., 1996
HLM122  ± 323-a 5.9  ± 0.458–9863-a 3-b 2.2–9.43-b Gorski et al., 1994; Kerry et al., 1994; Dayer et al., 1989; Ching et al., 1995; Jacqz-Aigrain et al., 1993; Schmider et al., 1997
CYP2D6B-lymphoblasts4.4  ± 0.11.3  ± 0.1
E. coli membranes4.7  ± 0.12.3  ± 0.2
Other0.5 5.4 Ching et al., 1995
HLM205  ± 15157  ± 2763–20003-a 44–88 Riley and Howbrook 1998; Wang et al., 1997; Gorski et al., 1994
CYP3A4B-lymphoblasts1.6  ± 0.138  ± 6130 ± 63-a, 220 ± 103-a 33 ± 4, 46 ± 5 Riley and Howbrook, 1998;Wang et al., 1997
E. coli membranes2.5  ± 0.118  ± 1
  • 3-a values in pmol/min/mg.

  • 3-b reflects Km and Vmaxof high-affinity component.

  • 3-c double-plasmid system.

  • 3-d single-plasmid system.

  • Probe reactions for isoforms indicated were CYP1A2-EROD, CYP2C9-naproxen O-demethylation, CYP2C19-diazepamN-demethylation, CYP2D6-dextromethorphanO-demethylation, and CYP3A4 N-demethylation.