TABLE 2.

Kinetic constants for menadione, benzoquinone, and NADPH in the presence of a saturating second substratea

SubstrateSaturating second substrateKm (μM)kcat (s−1)kcat/Km(M−1 s−1)
MenadioneNADPH14.4 ± 2.4122 ± 128.4 (±1.6) × 106
BenzoquinoneNADPH82.7 ± 18.6474 ± 535.7 (±1.4) × 106
NADPHMenadione26.3 ± 3.5115 ± 124.4 (±0.7) × 106
  • a The kinetic constants presented are computed from the plots depicted in Fig. 3 and 4. Values are means and standard deviations.