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Related Concept Videos

Radical Formation: Abstraction00:47

Radical Formation: Abstraction

3.3K
The electron of an atom can be abstracted from a compound by a relatively unstable radical to generate a new radical of relatively greater stability. For example, an initiator which forms radicals by homolysis can abstract a suitable species like a hydrogen atom or a halogen atom from a compound to generate a new radical. This ability of radicals to propagate by abstraction is a crucial feature of radical chain reactions.
Even though homolysis produces radicals, it is different from radical...
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Radical Formation: Elimination00:51

Radical Formation: Elimination

1.6K
Another method of radical formation is the elimination process. It is the opposite of the addition route and is driven by the instability of the radical. For example, as depicted in Figure 1, dibenzoyl peroxide yields a pair of unstable radicals upon homolysis. Given its instability, this radical spontaneously undergoes elimination via a C–C bond cleavage to form a relatively more stable phenyl radical. The mechanism involves cleavage of the bond between the α and β positions...
1.6K
Radical Formation: Homolysis00:54

Radical Formation: Homolysis

3.6K
A bond is formed between two atoms by sharing two electrons. When this bond is broken by supplying sufficient energy, either two electrons can be taken up by one atom forming ions by the cleavage called heterolysis, or the two electrons are shared by two atoms, with one each creating radicals by the cleavage called homolysis.
3.6K
Radical Reactivity: Overview01:11

Radical Reactivity: Overview

2.2K
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired...
2.2K
Radical Reactivity: Intramolecular vs Intermolecular01:33

Radical Reactivity: Intramolecular vs Intermolecular

1.4K
Radical reactions can occur either intermolecularly or intramolecularly. In an intermolecular radical reaction, a nucleophilic radical adds to an electrophilic alkene or vice versa. In such reactions, the radical and generally the alkene, which is also called the radical trap, are two different molecules. Additionally, for such intermolecular reactions to occur, the radical trap must be active, present in an excess concentration, and the radical starting material must have a weak...
1.4K
Radical Reactivity: Steric Effects01:10

Radical Reactivity: Steric Effects

1.6K
The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic...
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Updated: May 2, 2026

Monitoring Equilibrium Changes in RNA Structure by 'Peroxidative' and 'Oxidative' Hydroxyl Radical Footprinting
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BLUF domain function does not require a metastable radical intermediate state.

Andras Lukacs1, Richard Brust, Allison Haigney

  • 1Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States.

Journal of the American Chemical Society
|March 4, 2014
PubMed
Summary
This summary is machine-generated.

Photoinduced electron transfer (PET) is not central to blue light using flavin (BLUF) protein function. Studies show radical intermediates are not observed or correlated with photoactivity, suggesting alternative nonradical pathways.

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Area of Science:

  • Biochemistry
  • Photochemistry
  • Molecular Biology

Background:

  • Blue light using flavin (BLUF) proteins are crucial blue light sensors in cells.
  • The initial light-activated step in BLUF proteins remains unclear.
  • Photoinduced electron transfer (PET) involving tyrosine and flavin is a proposed mechanism.

Purpose of the Study:

  • Investigate the role of PET in the photocycle of three BLUF proteins.
  • Determine if radical intermediates formed via PET are essential for BLUF protein function.

Main Methods:

  • Ultrafast broadband transient infrared spectroscopy to monitor photochemical dynamics.
  • Site-directed mutagenesis and isotope labeling to identify radical intermediates.
  • Unnatural amino acid mutagenesis to alter electron transfer driving force.

Main Results:

  • Radical intermediates indicative of PET were not consistently observed in two of three BLUF proteins studied.
  • Mutational analysis and isotope labeling confirmed the presence of flavin and protein radical states.
  • Altering the driving force for PET via fluorotyrosine substitution did not yield results consistent with a PET mechanism.

Conclusions:

  • Observed PET intermediates in BLUF proteins are not correlated with photoactivity.
  • Radical intermediates are unlikely to be central to the operational mechanism of BLUF proteins.
  • Nonradical pathways, such as keto-enol tautomerization, are plausible alternatives for BLUF protein photoactivation.