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Updated: Mar 30, 2026
14:27
Steady-state, Pre-steady-state, and Single-turnover Kinetic Measurement for DNA Glycosylase Activity
Published on: August 19, 2013
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Enzyme-substrate-inactivator complex formation can impact time-dependent inhibition kinetics
Jaydeep Yadav1, Jan Wahlstrom2, Ken Korzekwa3
1Department of Pharmacokinetics, Dynamics, Metabolism, and Bioanalytics, Merck & Co, Inc, Rahway, New Jersey.
Summary
Accurate drug-drug interaction (DDI) prediction requires evaluating time-dependent inhibition (TDI) of cytochrome P450. This study shows that incorporating enzyme-substrate-inhibitor complex formation in models improves TDI parameter estimation and DDI prediction accuracy.
Area of Science:
- Pharmacology and Drug Metabolism
- Computational Chemistry and Bioinformatics
Background:
- Accurate prediction of drug-drug interactions (DDIs) is crucial in drug discovery.
- Time-dependent inhibition (TDI) of cytochrome P450 enzymes is a key factor in DDIs.
- In vitro TDI parameters (KI and kinact) are used to predict clinical DDIs.
Purpose of the Study:
- To evaluate the impact of enzyme-substrate-inhibitor (ESI) complex formation on TDI parameter estimation.
- To assess how incorporating ESI formation affects DDI predictions.
- To improve the accuracy of in vivo DDI predictions by accounting for in vitro kinetic complexities.
Main Methods:
- Numerical analysis of 13 in vitro TDI datasets exhibiting non-Michaelis-Menten kinetics.
- Modeling TDI parameters (KI and kinact) with and without considering ESI complex formation.
- Comparison of inactivation efficiency and DDI predictions between the two modeling approaches.
Main Results:
- The difference in inactivation efficiency between models with and without ESI ranged from 0.67 to 2.94-fold.
- Accounting for ESI formation led to varying DDI predictions, from moderate to strong, for the same compounds.
- Observed kinetic complexities, such as activation and biphasic inactivation, were successfully modeled by including ESI.
Conclusions:
- In vitro TDI models should incorporate enzyme-substrate-inhibitor complex formation to accurately reflect kinetic complexities.
- Simultaneous modeling of activation, substrate-dependent kinetics, and TDI enhances the reliability of DDI predictions.
- This approach improves confidence in predicting clinical DDIs by providing more accurate in vivo estimations.
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