Related Experiment Video
Updated: Sep 22, 2025
08:00
DNA Nanotubes as a Versatile Tool to Study Semiflexible Polymers
Published on: October 25, 2017
7.0K
Polymer Looping Is Controlled by Macromolecular Crowding, Spatial Confinement, and Chain Stiffness.
Jaeoh Shin1,2, Andrey G Cherstvy1, Ralf Metzler1,3
1Institute for Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany.
ACS Macro Letters
|May 21, 2022
Summary
Computer simulations reveal how polymer stiffness and crowding affect DNA looping. Crowding slows flexible DNA looping but can speed up or slow down stiff DNA looping, depending on length and confinement.
Area of Science:
- Polymer physics
- Biophysics
- Computational chemistry
Background:
- Macromolecular crowding and confinement significantly influence polymer behavior within cellular environments.
- Understanding polymer looping is crucial for biological processes like gene regulation.
Purpose of the Study:
- To investigate the looping characteristics of linear polymers with varying persistence lengths under crowding conditions within a spherical cavity.
- To elucidate the distinct effects of macromolecular crowding on flexible versus stiff polymers.
Main Methods:
- Extensive computer simulations were employed to model polymer behavior.
- Analysis focused on looping probability and looping time as functions of chain length and stiffness.
Main Results:
- Stiff chains exhibit oscillating patterns in looping probability and time with changing chain length.
- Crowding effects vary: flexible chains show slowed looping kinetics, while stiff chains experience either decreased or facilitated kinetics.
- Severe confinement can strongly facilitate looping kinetics for stiff polymers.
Conclusions:
- Polymer stiffness and macromolecular crowding play complex, length-dependent roles in polymer looping.
- Findings have significant implications for understanding DNA looping dynamics within the crowded cellular interior.
Related Concept Videos
01:14Polymer Classification: Architecture
3.1K
Polymers are classified as linear or branched on the basis of their chain architecture. The polymer chains in linear polymers have a long chain-like structure with minimal to no branching at all. Even if a polymer features large substituent groups on the monomer, which appear as branches to the skeleton, it is not considered a branched polymer. A branched polymer contains secondary polymer chains that arise from the main polymer chain. The branching occurs when the polymer growth shifts from...
3.1K
01:17Radical Chain-Growth Polymerization: Chain Branching
2.0K
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...
2.0K
00:57Cationic Chain-Growth Polymerization: Mechanism
2.4K
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the...
2.4K
01:09Radical Chain-Growth Polymerization: Mechanism
2.8K
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...
2.8K
01:20Anionic Chain-Growth Polymerization: Overview
2.2K
The polymerization process that involves carbanion as an intermediate is called anionic polymerization. It is also a type of addition or chain-growth polymerization. Anionic polymerization gets initiated by a strong nucleophile such as an organolithium or a Grignard reagent. The most commonly used initiator for anionic polymerization is butyl lithium. Monomers involved in anionic polymerization must possess a vinyl group bonded to one or two electron-withdrawing groups. For instance,...
2.2K
01:04Anionic Chain-Growth Polymerization: Mechanism
2.1K
The mechanism for anionic chain-growth polymerization involves initiation, propagation, and termination steps. In the initiation step, a nucleophilic anion, such as butyl lithium, initiates the polymerization process by attacking the π bond of the vinylic monomer. As a result, a carbanion, stabilized by the electron‐withdrawing group, is generated. The resulting carbanion acts as a Michael donor in the propagation step and attacks the second vinylic monomer, which acts as a Michael...
2.1K