Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Induced-fit Model01:13

Induced-fit Model

77.0K
Most chemical reactions in cells require enzymes—biological catalysts that speed up the reaction without being consumed or permanently changed. They reduce the activation energy needed to convert the reactants into products. Enzymes are proteins, that usually work by binding to a substrate—a reactant molecule that they act upon.
Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical...
77.0K
Enzyme Inhibition01:30

Enzyme Inhibition

72.4K
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.
72.4K
Enzymes02:34

Enzymes

68.9K
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.
Enzyme deficiencies can often translate into life-threatening diseases. For example, a genetic abnormality resulting in the deficiency of the enzyme G6PD...
68.9K
Introduction to Enzymes01:22

Introduction to Enzymes

25.2K
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.’
Most enzymes are proteins that speed up biochemical reactions without being consumed. Enzymes contain one or more active sites that...
25.2K
Catalytically Perfect Enzymes01:07

Catalytically Perfect Enzymes

4.3K
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...
4.3K
Introduction to Mechanisms of Enzyme Catalysis01:13

Introduction to Mechanisms of Enzyme Catalysis

9.0K
For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes...
9.0K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Formate Dehydrogenase: The Role of the AMP Cofactor Fragment in Stabilization of the Transition State for Enzyme-Catalyzed Hydride Transfer.

ACS omegaยท2026
Same author

Enzyme Architecture: Activation of Phosphite Dehydrogenase-Catalyzed Hydride Transfer by NAD<sup>+</sup> Cofactor Fragments.

Biochemistryยท2025
Same author

The Role of Protein Side Chains in Enzyme-Activating Conformational Changes: Lessons from Studies on Variant Enzymes.

Chemical reviewsยท2025
Same author

Bill Jencks' Model for Lifetime Enforced Changes in Reaction Mechanism: A Legacy for Physical Organic Chemistry.

Chemphyschem : a European journal of chemical physics and physical chemistryยท2025
Same author

Glycerol 3-Phosphate Dehydrogenase Catalyzed Hydride Transfer: Enzyme Activation by Cofactor Pieces.

Biochemistryยท2024
Same author

Changes in Mechanism and Transition State Structure for Solvolysis Reactions of Ring Substituted Benzyl Chlorides in Aqueous Solution.

Journal of physical organic chemistryยท2024

Related Experiment Video

Updated: May 4, 2026

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
09:42

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

Published on: January 16, 2016

9.3K

Punching holes in an enzyme.

John P Richard1

  • 1Department of Chemistry, The State University of New York at Buffalo, Buffalo, NY 14260-3000, USA. jrichard@buffalo.edu

Chemistry & Biology
|September 26, 2009
PubMed
Summary

Researchers created enzyme variants of human purine nucleoside phosphorylase by replacing aromatic amino acids with glycine. These modified enzymes reveal previously hidden chemical processes occurring within the enzyme active site.

Area of Science:

  • Biochemistry
  • Enzymology
  • Protein Engineering

Background:

  • Human purine nucleoside phosphorylase (HPNP) is a key enzyme in purine metabolism.
  • Understanding HPNP's active site chemistry is crucial for therapeutic development.
  • Previous studies focused on substrate interactions, with less known about conformational dynamics.

Discussion:

  • Substitution of aromatic residues with glycine at the HPNP lid created 'holes', altering enzyme structure.
  • These structural modifications provide novel insights into enzyme active site dynamics.
  • The 'holed' enzymes facilitate the observation of transient chemical intermediates.

Key Insights:

  • The study demonstrates that targeted protein engineering can expose cryptic active site chemistry.

More Related Videos

Fast Enzymatic Processing of Proteins for MS Detection with a Flow-through Microreactor
09:49

Fast Enzymatic Processing of Proteins for MS Detection with a Flow-through Microreactor

Published on: April 6, 2016

7.3K
Multi-enzyme Screening Using a High-throughput Genetic Enzyme Screening System
08:10

Multi-enzyme Screening Using a High-throughput Genetic Enzyme Screening System

Published on: August 8, 2016

8.3K

Related Experiment Videos

Last Updated: May 4, 2026

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
09:42

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

Published on: January 16, 2016

9.3K
Fast Enzymatic Processing of Proteins for MS Detection with a Flow-through Microreactor
09:49

Fast Enzymatic Processing of Proteins for MS Detection with a Flow-through Microreactor

Published on: April 6, 2016

7.3K
Multi-enzyme Screening Using a High-throughput Genetic Enzyme Screening System
08:10

Multi-enzyme Screening Using a High-throughput Genetic Enzyme Screening System

Published on: August 8, 2016

8.3K
  • Glycine substitutions at the HPNP lid are effective in probing enzyme mechanisms.
  • Hidden chemical reactions, previously inaccessible to study, are now observable.

    • Outlook:

    • Further investigation of these engineered HPNP variants could reveal novel catalytic mechanisms.
    • This approach may be applicable to other enzymes to uncover their hidden chemistry.
    • Understanding these processes could lead to the design of more effective HPNP inhibitors or activators.