TABLE 1

Kinetic parameters of lithocholic acid metabolite formation by rat hepatic microsomes

Kinetic parameters were derived from the metabolite formation data presented in Fig. 3. Values represent the mean ± S.E.M. of triplicate determinations.

Metabolite
Apparent Vmax
Apparent Km
Apparent K′
n
Apparent Ki
pmol/min/mg protein μM μM μM
MDCAa 5920 ± 1180 56.0 ± 17.8 N.A. N.A. 194 ± 74.6
ILCAb 803 ± 91.8 N.A. 29.3 ± 5.9 2.3 ± 0.8 N.A.
3KCAb 413 ± 25.8 N.A. 71.6 ± 6.5 2.5 ± 0.6 N.A.
6KLCAc 44.5 ± 2.1 1.6 ± 0.3 N.A. N.A. N.A.
UDCAc
22.4 ± 1.7
15.3 ± 3.7
N.A.
N.A.
N.A.

  • N.A., not applicable.

  • ↵ a Kinetic parameters for MDCA formation were calculated using the substrate inhibition kinetics model (eq. 2).

  • ↵ b Kinetic parameters for ILCA and 3KCA formation were calculated using the sigmoidal kinetics model, Hill equation (eq. 1).

  • ↵ c Kinetic parameters for 6KLCA and UDCA formation were calculated using the Michaelis-Menten equation.