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Related Concept Videos

Enzyme Kinetics01:19

Enzyme Kinetics

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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...
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Enzymes02:34

Enzymes

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Inside living organisms, enzymes act as catalysts for many biochemical reactions involved in cellular metabolism. The role of enzymes is to reduce the activation energies of biochemical reactions by forming complexes with its substrates. The lowering of activation energies favor an increase in the rates of biochemical reactions.
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Introduction to Enzymes01:22

Introduction to Enzymes

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The use of enzymes by humans dates to 7000 BCE. Humans first used enzymes to ferment sugars and produce alcohol without knowing that this was an enzyme-catalyzed reaction. Wilhelm Kuhne coined the term 'enzyme' in 1877 from the Greek words ‘en’ meaning ‘in’ or ‘within’ and ‘zyme’ meaning ‘yeast.’
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Enzyme Inhibition01:30

Enzyme Inhibition

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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.
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Enzymes and Activation Energy01:13

Enzymes and Activation Energy

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The activation energy (or free energy of activation), abbreviated as Ea, is the small amount of energy input necessary for all chemical reactions to occur. During chemical reactions, certain chemical bonds break, and new ones form. For example, when a glucose molecule breaks down, bonds between the molecule's carbon atoms break. Since these are energy-storing bonds, they release energy when broken. However, the molecule must be somewhat contorted to get into a state that allows the bonds to...
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Catalytically Perfect Enzymes01:07

Catalytically Perfect Enzymes

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The theory of catalytically perfect enzymes was first proposed by W.J. Albery and J. R. Knowles in 1976. These enzymes catalyze biochemical reactions at high-speed. Their catalytic efficiency values range from 108-109 M-1s-1. These enzymes are also called 'diffusion-controlled' as the only rate-limiting step in the catalysis is that of the substrate diffusion into the active site. Examples include triose phosphate isomerase, fumarase, and superoxide dismutase.
 
Most enzymes...
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Related Experiment Video

Updated: Jan 4, 2026

Single Liposome Measurements for the Study of Proton-Pumping Membrane Enzymes Using Electrochemistry and Fluorescent Microscopy
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Single Liposome Measurements for the Study of Proton-Pumping Membrane Enzymes Using Electrochemistry and Fluorescent Microscopy

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Enzymatic activity in single cells.

Josephine Geertsen Keller1, Magnus Stougaard2, Birgitta R Knudsen3

  • 1Department of Clinical Medicine, Pathology, Aarhus University Hospital, Aarhus C, Denmark; Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark.

Methods in Enzymology
|November 1, 2019
PubMed
Summary

This study introduces a sensitive method to measure human topoisomerase 1 (TOP1) activity in single cancer stem cells. The On-Slide Rolling circle Enhanced Enzyme Activity Detection (REEAD) technique enables precise single-cell analysis for cancer research.

Keywords:
CancerCancer stem cellsEnzyme activityHuman topoisomerase 1Microscopic slidesRolling circle amplificationSingle cell detection

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A Microfluidic Chip for the Versatile Chemical Analysis of Single Cells
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Metabolic Mapping: Quantitative Enzyme Cytochemistry and Histochemistry to Determine the Activity of Dehydrogenases in Cells and Tissues
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Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cancer Research

Background:

  • Understanding cell-to-cell variations is crucial for complex biological systems.
  • Single-cell analysis is vital for detailed biological investigations.
  • Human topoisomerase 1 (TOP1) plays a role in cellular processes.

Purpose of the Study:

  • To develop a highly sensitive method for measuring TOP1 activity in single cells.
  • To analyze TOP1 activity in CD133 positive DLD-1 cells.
  • To facilitate research into cancer stem cell chemoresistance.

Main Methods:

  • Developed On-Slide Rolling circle Enhanced Enzyme Activity Detection (REEAD).
  • Utilized dual functionalized glass slides with anti-CD133 antibodies and DNA primers.
  • Employed specific capture and lysis of CD133 positive cells.

Main Results:

  • Demonstrated direct quantitative measurement of TOP1 activity.
  • Achieved highly sensitive detection of TOP1 activity in single CD133 positive DLD-1 cells.
  • Validated the REEAD method for single-cell enzyme activity analysis.

Conclusions:

  • The On-Slide REEAD protocol offers a novel approach for single-cell analysis.
  • This method enhances the study of enzyme activity at the single-cell level.
  • It is expected to advance research on cancer stem cell chemoresistance.