Kinetic study of cytochrome P450 3A4 activity on warfarin by capillary electrophoresis with fluorescence detection |
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Authors: | Zhang Jie Ha Pham Thi Thanh Lou Yijia Hoogmartens Jos a Van Schepdael Ann |
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Affiliation: | Laboratory of Pharmaceutical Chemistry and Drug Analysis, Faculty of Pharmaceutical Sciences, K. U. Leuven, Van Evenstraat 4, B-3000 Leuven, Belgium. |
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Abstract: | The use of capillary electrophoresis (CE) for the determination of cytochrome P450 3A4 (CYP3A4) activity with R-warfarin as a substrate was investigated. CYP3A4 activity was determined by the quantitation of the product, 10-hydroxywarfarin, based on separation by CE. The separation conditions were as follows: capillary, 80.5 cm (75 microm i.d., 60 cm effective length); 50 mM sodium phosphate buffer (pH 6.5); 23 kV (90 microA) applied voltage; fluorescence detection, excitation wavelength, 310 nm, emission wavelength, 418 nm; capillary temperature, 37 degrees C. With the developed CYP3A4 activity assay and the Lineweaver-Burk equation, the Michaelis-Menten parameters Km and Vmax for formation of 10-hydroxywarfarin from R-warfarin in the presence of CYP3A4 were calculated to be 166 +/- 12 microM and 713 +/- 14 pmol/min/nmol (or 91.4 pmol/min/mg) CYP3A4, respectively. |
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Keywords: | Kinetic study Michaelis–Menten analysis Enzyme CYP3A4 |
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