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

Oxidation of Phenols to Quinones01:17

Oxidation of Phenols to Quinones

4.3K
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox...
4.3K
Pyruvate Oxidation01:15

Pyruvate Oxidation

167.8K
After glycolysis, the charged pyruvate molecules enter the mitochondria via active transport and undergo three enzymatic reactions. These reactions ensure that pyruvate can enter the next metabolic pathway so that energy stored in the pyruvate molecules can be harnessed by the cells.
First, the enzyme pyruvate dehydrogenase removes the carboxyl group from pyruvate and releases it as carbon dioxide. The stripped molecule is then oxidized and releases electrons, which are then picked up by NAD+...
167.8K
Oxidation of Alcohols02:37

Oxidation of Alcohols

15.4K
In this lesson, the oxidation of alcohols is discussed in depth. The various reagents used for oxidation of primary and secondary alcohols are detailed, and their mechanism of action is provided.
The process of oxidation in a chemical reaction is observed in any of the three forms:
15.4K
Regioselectivity of Electrophilic Additions-Peroxide Effect02:35

Regioselectivity of Electrophilic Additions-Peroxide Effect

10.0K
In the presence of organic peroxides, the addition of hydrogen bromide to an alkene yields the isomer that is not predicted by Markovnikov’s rule. For example, the addition of hydrogen bromide to 2-methylpropene in the presence of peroxides gives 1-bromo-2-methylpropane. This addition reaction proceeds via a free radical mechanism, which reverses the regioselectivity. The free radical reaction mechanism involves three stages: initiation, propagation, and termination.
10.0K
Catalytically Perfect Enzymes01:07

Catalytically Perfect Enzymes

4.8K
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...
4.8K
Regioselective Formation of Enolates01:33

Regioselective Formation of Enolates

3.3K
As depicted in the figure below, the unsymmetrical ketones can form two possible enolates:  less substituted or more substituted enolates. Usually, the thermodynamic enolates are formed from the more substituted α-carbon atom, while the kinetic enolates are formed faster by deprotonation from the less substituted position. The thermodynamic enolates have lower energy, so they are  more stable. But the energy required to form kinetic enolates is less.
3.3K

You might also read

Related Articles

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

Sort by
Same author

Structural basis of allosteric activation of Mycobacterium tuberculosis isocitrate lyase 2.

Communications biology·2026
Same author

Restoration of meropenem efficacy against multidrug-resistant Acinetobacter baumannii by green tea polyphenol EGCG: Dual targeting of efflux and porin pathways.

Phytomedicine : international journal of phytotherapy and phytopharmacology·2026
Same author

Structural remodelling of the 2OG oxygenase Rv3406 enables sulfur-scavenging in <i>Mycobacterium tuberculosis</i>.

Chemical communications (Cambridge, England)·2025
Same author

Protease mimicry: Dissecting the ester bond crosslinking mechanics in bacterial adhesin proteins.

Protein science : a publication of the Protein Society·2025
Same author

Premium ultra-trace analytical method for part per quadrillion (ppq) PFAS quantification in drinking water.

Analytica chimica acta·2025
Same author

An integrated structural and biophysical approach to study carbon metabolism in <i>Mycobacterium tuberculosis</i>.

QRB discovery·2025

Related Experiment Video

Updated: Dec 20, 2025

Defining Substrate Specificities for Lipase and Phospholipase Candidates
08:59

Defining Substrate Specificities for Lipase and Phospholipase Candidates

Published on: November 23, 2016

15.4K

Substrate specificity of polyphenol oxidase.

Mark-Anthony McLarin1, Ivanhoe K H Leung1,2,3

  • 1School of Chemical Sciences, The University of Auckland, Auckland, New Zealand.

Critical Reviews in Biochemistry and Molecular Biology
|May 23, 2020
PubMed
Summary

Polyphenol oxidase (PPO) enzymes are crucial in browning and pigmentation. This review explores recent structural and mechanistic studies to understand PPO substrate specificity, a long-standing puzzle.

Keywords:
Catechol oxidasePolyphenol oxidaseTyrosinaseenzyme mechanismsubstrate specificity

More Related Videos

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

9.2K
Author Spotlight: Eco-Friendly Extraction of Bioactive Compounds Using Polyol-Based Microwave-Assisted Techniques
07:05

Author Spotlight: Eco-Friendly Extraction of Bioactive Compounds Using Polyol-Based Microwave-Assisted Techniques

Published on: August 23, 2024

2.6K

Related Experiment Videos

Last Updated: Dec 20, 2025

Defining Substrate Specificities for Lipase and Phospholipase Candidates
08:59

Defining Substrate Specificities for Lipase and Phospholipase Candidates

Published on: November 23, 2016

15.4K
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

9.2K
Author Spotlight: Eco-Friendly Extraction of Bioactive Compounds Using Polyol-Based Microwave-Assisted Techniques
07:05

Author Spotlight: Eco-Friendly Extraction of Bioactive Compounds Using Polyol-Based Microwave-Assisted Techniques

Published on: August 23, 2024

2.6K

Area of Science:

  • Biochemistry
  • Enzymology

Background:

  • Polyphenol oxidase (PPO) is a type-3 copper enzyme involved in fruit browning, mammalian pigmentation, and biotechnological applications.
  • Despite extensive research, PPO substrate specificity remains poorly understood, with several theories proposed.

Purpose of the Study:

  • To review recent advancements in structural and mechanistic studies of PPOs.
  • To consolidate current understanding of PPO substrate specificity.

Main Methods:

  • Review of existing literature on PPO structural and mechanistic studies.
  • Analysis of proposed theories for PPO substrate specificity, including the "blocker residue" and "second shell" theories.

Main Results:

  • Recent studies provide new insights into PPO structure and mechanism.
  • Key concepts regarding substrate specificity are being consolidated.

Conclusions:

  • Understanding PPO substrate specificity is critical for inhibitor development and biotechnological applications.
  • Further research integrating structural, mechanistic, and computational approaches is needed to fully elucidate PPO substrate specificity.