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

Radical Chain-Growth Polymerization: Chain Branching01:17

Radical Chain-Growth Polymerization: Chain Branching

2.6K
The skeletal structure of polymers synthesized via radical polymerization is always branched. For example, the polymerization of ethylene by radical polymerization results in a low-density grade of polyethylene with a heavily branched skeletal structure. Here, the radical site abstracts hydrogen from the growing chain, and the radical site shifts from the end (a primary carbon center) to anywhere within the growing chain (a secondary carbon center). Consequently, the part of the chain from the...
2.6K
Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule02:17

Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule

18.4K
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
18.4K
Restarting Stalled Replication Forks02:37

Restarting Stalled Replication Forks

6.5K
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart,...
6.5K
Long-patch Base Excision Repair01:02

Long-patch Base Excision Repair

8.3K
Since the discovery of the two BER pathways, there has been a debate about how a cell chooses one pathway over the other and the factors determining this selection. Numerous in vitro experiments have pointed out multiple determinants for the sub-pathway selection. These are:
8.3K
Radical Chain-Growth Polymerization: Mechanism01:09

Radical Chain-Growth Polymerization: Mechanism

3.8K
The radical chain-growth polymerization mechanism consists of three steps: initiation, propagation, and termination of polymerization. The polymerization initiates when a free radical generated from the radical initiator adds to the unsaturated bond in the monomer. The unpaired electron of the free radical and one π electron in the unsaturated bond creates a σ bond between the free radical and the monomer. As a result, the other π electron in the unsaturated bond converts this species into...
3.8K
Restriction Enzymes01:11

Restriction Enzymes

38.9K
Restriction enzymes are bacterial enzymes used to cut DNA in a sequence-specific manner. To cleave DNA, they bind to specific palindromic sequences called restriction sites. Such palindromic DNA sequences or inverted repeats are commonly found in regions of functional significance, such as the origin of replication, gene operator sites, and regions containing transcription termination signals.
The host bacteria protect their own genomic DNA from these enzymes by methylating these sites. Some...
38.9K

You might also read

Related Articles

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

Sort by
Same author

Toward a Comparable Reactivity Framework for Type I Photoinitiators in Photocleavage, Photopolymerization and Light-Driven Additive Manufacturing.

Journal of the American Chemical Society·2026
Same author

Mapping the Molecular Universe: Exploring Chemical Compound Space by Multiscale High-Throughput Screening and Machine Learning.

Journal of chemical information and modeling·2026
Same author

Structural Modulation of TpPa‑1 Covalent Organic Framework in Flow Synthesis Guided by Green Chemistry Principles.

ACS engineering Au·2026
Same author

Enzymatic Encoding of Topology in an Intrinsically Disordered Single-Chain Protein.

Angewandte Chemie (International ed. in English)·2026
Same author

Macromolecules with Tunable Fluorescence via Photochemical Step-Growth Polymerization.

ACS macro letters·2026
Same author

Understanding Wavelength-Dependent Photopolymerizations via Nano-Second Resolved Transient Spectroscopy.

Journal of the American Chemical Society·2026

Related Experiment Video

Updated: Mar 28, 2026

In Vitro Directed Evolution of a Restriction Endonuclease with More Stringent Specificity
09:16

In Vitro Directed Evolution of a Restriction Endonuclease with More Stringent Specificity

Published on: March 25, 2020

7.8K

Entropy-Driven Selectivity for Chain Scission: Where Macromolecules Cleave.

Kai Pahnke1,2, Josef Brandt3,4, Ganna Gryn'ova5,6

  • 1Preparative Macromolecular Chemistry, Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology (KIT), Engesserstrasse 18, 76131, Karlsruhe, Germany.

Angewandte Chemie (International Ed. in English)
|December 15, 2015
PubMed
Summary
This summary is machine-generated.

Bond cleavage in the middle of molecules is entropically favored over end cleavage. This finding impacts polymer degradation and chain transfer, with implications across chemistry.

Keywords:
cycloadditionsentropic effectspolymerssupramolecular chemistrythermodynamics

More Related Videos

Parallel High Throughput Single Molecule Kinetic Assay for Site-Specific DNA Cleavage
06:51

Parallel High Throughput Single Molecule Kinetic Assay for Site-Specific DNA Cleavage

Published on: May 6, 2020

4.4K
A Method for Selecting Structure-switching Aptamers Applied to a Colorimetric Gold Nanoparticle Assay
12:31

A Method for Selecting Structure-switching Aptamers Applied to a Colorimetric Gold Nanoparticle Assay

Published on: February 28, 2015

15.8K

Related Experiment Videos

Last Updated: Mar 28, 2026

In Vitro Directed Evolution of a Restriction Endonuclease with More Stringent Specificity
09:16

In Vitro Directed Evolution of a Restriction Endonuclease with More Stringent Specificity

Published on: March 25, 2020

7.8K
Parallel High Throughput Single Molecule Kinetic Assay for Site-Specific DNA Cleavage
06:51

Parallel High Throughput Single Molecule Kinetic Assay for Site-Specific DNA Cleavage

Published on: May 6, 2020

4.4K
A Method for Selecting Structure-switching Aptamers Applied to a Colorimetric Gold Nanoparticle Assay
12:31

A Method for Selecting Structure-switching Aptamers Applied to a Colorimetric Gold Nanoparticle Assay

Published on: February 28, 2015

15.8K

Area of Science:

  • Chemical Physics
  • Polymer Chemistry
  • Supramolecular Chemistry

Background:

  • Understanding bond dissociation selectivity is crucial for controlling chemical reactions.
  • Entropic factors significantly influence molecular behavior and reaction pathways.

Purpose of the Study:

  • To investigate the entropic preference for bond cleavage in the middle versus the end of molecules.
  • To explore the implications of this selectivity in covalent and supramolecular systems.

Main Methods:

  • Theoretical modeling to predict entropic effects.
  • High-temperature (HT) Nuclear Magnetic Resonance (NMR) spectroscopy of supramolecular systems.
  • Temperature-dependent size-exclusion chromatography (TD SEC) of polymers.

Main Results:

  • Bond cleavage at the molecular center is significantly more entropically favorable than at the molecular end.
  • Experimental evidence supports theoretical predictions of entropic selectivity.
  • Demonstrated selectivity in both self-assembled supramolecular diblock systems and Diels-Alder polymers.

Conclusions:

  • Molecular bond cleavage exhibits inherent entropic selectivity, favoring central dissociation.
  • This entropic effect has broad implications for polymer degradation, chain transfer, and chemical control agents.
  • The findings provide a fundamental understanding of dissociation mechanisms in various chemical systems.