Kinetic parameters for activation of meloxicam metabolism by human CYP 3A4 by quinidine and hydroquinidine
| Quinidine | Hydroquinidine | |
|---|---|---|
| V max(pmol/min/mg protein) | 13 | 11 |
| K s(μM) | 310 | 270 |
| K a (μM) | 50 | 32 |
| α | 0.42 | 0.33 |
| β | 7.3 | 9.3 |
| B | 0.9968 | 0.9999 |
Experimental data obtained in the presence of activator (A) were fitted to the velocity equation for mixed-type nonessential activation. Vmax, maximal velocity of the unactivated reaction; Ks, dissociation constant of the enzyme-substrate complex; Ka, dissociation constant of the enzyme-activator complex; β, factor by whichVmax changes when A occupies the enzyme; α, factor by which Ks changes when Aoccupies the enzyme.