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Related Concept Videos

Introduction to Enzyme Kinetics01:19

Introduction to Enzyme Kinetics

26.2K
Enzyme kinetics studies the rates of biochemical reactions. Scientists monitor the reaction rates for a particular enzymatic reaction at various substrate concentrations. Additional trials with inhibitors or other molecules that affect the reaction rate may also be performed.
The experimenter can then plot the initial reaction rate or velocity (Vo) of a given trial against the substrate concentration ([S]) to obtain a graph of the reaction properties. For many enzymatic reactions involving a...
26.2K
Enzyme Kinetics01:19

Enzyme Kinetics

101.0K
Enzymes speed up reactions by lowering the activation energy of the reactants. The speed at which the enzyme turns reactants into products is called the rate of reaction. Several factors impact the rate of reaction, including the number of available reactants. Enzyme kinetics is the study of how an enzyme changes the rate of a reaction.
Scientists typically study enzyme kinetics with a fixed amount of enzyme in the controlled environment of a test tube. When more reactant, or substrate, is...
101.0K
Determination of Michaelis Constant and Maximum Elimination Rate01:20

Determination of Michaelis Constant and Maximum Elimination Rate

209
The Michaelis constant (KM) and the theoretical maximum process rate (Vmax) are vital parameters in the Michaelis-Menten equation, central to many biochemical reactions. They provide essential insights into enzyme kinetics and drug metabolism.
These parameters can be estimated by analyzing plasma concentration data post-drug administration. A notable example of this application is phenytoin, a drug with capacity-limited kinetics. It's recommended that phenytoin should be administered at two...
209
Enzyme Inhibition01:30

Enzyme Inhibition

86.1K
Inhibitors are molecules that reduce enzyme activity by binding to the enzyme. In a normally functioning cell, enzymes are regulated by a variety of inhibitors. Drugs and other toxins can also inhibit enzymes. Some inhibitors bind to the enzyme’s active site, while others inhibit enzymatic activity by binding to other sites on the protein structure.
86.1K
Factors Affecting Drug Biotransformation: Biological01:19

Factors Affecting Drug Biotransformation: Biological

330
Biological factors significantly impact drug metabolism, influencing drug clearance, efficacy, and potential toxicity.
Species differences: Variations in enzyme systems across species can cause disparities in drug metabolism. For instance, humans may metabolize certain drugs faster than rodents, altering therapeutic effects.
Strain differences: Genetic variations within a species can result in differing enzyme activity, impacting drug response and toxicity. For example, some mouse strains may...
330
Turnover Number and Catalytic Efficiency01:19

Turnover Number and Catalytic Efficiency

15.2K
The turnover number of an enzyme is the maximum number of substrate molecules it can transform per unit time. Turnover numbers for most enzymes range from 1 to 1000 molecules per second. Catalase has the known highest turnover number, capable of converting up to 2.8×106 molecules of hydrogen peroxide into water and oxygen per second. Lysozyme has the lowest known turnover number of half a molecule per second.
Chymotrypsin is a pancreatic enzyme that breaks down proteins during digestion....
15.2K

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Related Experiment Video

Updated: Oct 28, 2025

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
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Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

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Variability in Human In Vitro Enzyme Kinetics.

Christopher R Gibson1, Ying-Hong Wang2, Ninad Varkhede3

  • 1Department of Pharmacokinetics, Pharmacodynamics and Drug Metabolism (PPDM), Merck Research Laboratories, West Point, PA, USA. Christopher_gibson@merck.com.

Methods in Molecular Biology (Clifton, N.J.)
|July 17, 2021
PubMed
Summary
This summary is machine-generated.

Human enzyme kinetic data variability stems from enzyme source, donor genetics, study design, and data analysis. Understanding these factors is crucial for accurate pharmacokinetic predictions.

Keywords:
Cytochrome P450Enzyme kineticsHepatocytesMicrosomesPharmacogeneticsUGTVariability

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Area of Science:

  • Pharmacology
  • Biochemistry
  • Enzyme Kinetics

Background:

  • Human in vitro enzyme kinetic data exhibit significant variability.
  • Factors influencing this variability include enzyme source, preparation, donor genetics, study design, and data analysis.
  • Comparing data across studies and laboratories is challenging due to inherent variability.

Purpose of the Study:

  • To comprehensively discuss factors contributing to variability in human in vitro enzyme kinetic data.
  • To highlight differences between native and recombinant enzyme systems and their impact on kinetic data.
  • To present approaches for visualizing uncertainty in enzyme kinetic data for pharmacokinetic predictions.

Main Methods:

  • Review and synthesis of factors affecting enzyme kinetic data.
  • Discussion of experimental design considerations.
  • Exploration of data analysis strategies.

Main Results:

  • Identified multiple sources of variability in human enzyme kinetic data.
  • Highlighted the impact of microenvironment differences in recombinant enzymes.
  • Presented methods for uncertainty visualization in pharmacokinetic modeling.

Conclusions:

  • Variability in human enzyme kinetic data is multifactorial and requires careful consideration.
  • Differences in experimental systems (e.g., native vs. recombinant microsomes) introduce variability.
  • Accurate pharmacokinetic predictions depend on understanding and visualizing data uncertainty.