TABLE 1

Kinetic constants for menadione metabolism by recombinant CBR1 wild-type and variant allele enzymes

Values correspond to mean ± S.D. obtained from three experiments performed with two independent enzyme preparations (n = 6) for each isoform.

Kinetic Parameter
CBR1 Wild-Type
V88I Variant
P131S Variant
Vmax (nmol/min · mg of protein) 537 ± 61 334 ± 9* 581 ± 68
Km (μM) 24 ± 10 18 ± 2 45 ± 15
kcat (s-1)a 0.30 0.19 0.33
kcat/Km (s-1 M-1)
12.8 × 103
10.5 × 103
7.3 × 103

  • ↵* Significantly different from wild type (p < 0.05).

  • ↵ a kcat calculated from Mr 34,000.