Related Experiment Video
Updated: Feb 14, 2026
05:57
Quantitative 31P NMR Analysis of Lignins and Tannins
Published on: August 2, 2021
14.8K
Laccase/Mediator Systems: Their Reactivity toward Phenolic Lignin Structures
Roelant Hilgers1, Jean-Paul Vincken1, Harry Gruppen1
1Laboratory of Food Chemistry, Wageningen University and Research, Wageningen 6708 WG, The Netherlands.
ACS Sustainable Chemistry & Engineering
|February 13, 2018
Summary
Mediators like ABTS significantly alter how laccase enzymes react with phenolic lignin subunits, promoting oxidation and coupling rather than polymerization, unlike HBT or laccase alone.
Area of Science:
- Biocatalysis
- Polymer Chemistry
- Enzymology
Background:
- Laccase-mediator systems (LMS) primarily target nonphenolic lignin subunits.
- Phenolic lignin subunits receive less attention, leaving their mediator-influenced reactions unclear.
- Understanding these reactions is crucial for lignin valorization.
Purpose of the Study:
- Investigate the influence of mediators on phenolic lignin subunit reactions.
- Compare the effects of HBT and ABTS in laccase-initiated reactions.
- Elucidate reaction pathways for phenolic lignin model compounds.
Main Methods:
- Utilized ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS).
- Studied reactions of a phenolic lignin dimer (GBG) with laccase from *Trametes versicolor*.
- Compared laccase alone, laccase/HBT, and laccase/ABTS systems.
Main Results:
- HBT showed negligible effect; laccase and laccase/HBT induced GBG polymerization.
- Laccase/ABTS exhibited higher GBG conversion rates due to direct oxidation and ABTS radical cation activity.
- Laccase/ABTS led to Cα oxidation and ABTS coupling with GBG, not polymerization.
Conclusions:
- Mediator choice critically impacts laccase activity on phenolic lignin subunits.
- ABTS promotes distinct reaction pathways (oxidation, coupling) compared to HBT or laccase alone.
- Proposed reaction mechanisms for phenolic lignin model compounds under different laccase-mediator conditions.
Related Concept Videos
02:23Structure and Nomenclature of Alcohols and Phenols
22.6K
Overview
Alcohols are one of the most important functional groups in organic chemistry. The name of alcohol comes from the hydrocarbon from which it is derived. Alcohols are organic molecules containing the functional hydroxyl or –OH group directly bonded to carbon. Phenols have an OH group directly attached to a benzene ring. While alcohols are colorless, phenol is a white crystalline compound with a characteristic "hospital smell" odor.
As with other organic compounds, alcohols and...
Alcohols are one of the most important functional groups in organic chemistry. The name of alcohol comes from the hydrocarbon from which it is derived. Alcohols are organic molecules containing the functional hydroxyl or –OH group directly bonded to carbon. Phenols have an OH group directly attached to a benzene ring. While alcohols are colorless, phenol is a white crystalline compound with a characteristic "hospital smell" odor.
As with other organic compounds, alcohols and...
22.6K
01:17Oxidation of Phenols to Quinones
4.8K
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...
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...
4.8K
02:32Physical Properties of Alcohols and Phenols
16.8K
Alcohols are organic compounds in which a hydroxy group is attached to a saturated carbon. Phenols are a class of alcohols containing a hydroxy group attached to an aromatic ring. The physical properties of the alcohols and phenols are influenced by hydrogen bonding due to the oxygen–hydrogen dipole in the hydroxy functional group and dispersion forces between alkyl or aryl regions of alcohol and phenol molecules.
Alcohols possess a higher boiling point than aliphatic hydrocarbons of similar...
Alcohols possess a higher boiling point than aliphatic hydrocarbons of similar...
16.8K
02:36Acidity and Basicity of Alcohols and Phenols
22.3K
Like water, alcohols are weak acids and bases. This is attributed to the polarization of the O–H bond making the hydrogen partially positive. Moreover, the electron pairs on the oxygen atom of alcohol make it both basic and nucleophilic. Protonation of an alcohol converts hydroxide, a poor leaving group, into water—a good one. The two acid–base equilibria corresponding to ethanol are depicted below.
22.3K
00:42Cross-reactivity
33.2K
Overview
33.2K
01:18Reactivity of Enols
4.2K
Enols are a class of compounds where a hydroxyl group is attached to a carbon–carbon double bond, which implies that it is a vinyl alcohol. A carbonyl compound with an α hydrogen undergoes keto–enol tautomerism and remains in equilibrium with its tautomer, the enol form. Usually, the keto tautomer is present in a higher concentration than the enol tautomer due to the higher bond energy of C=O compared to C=C. Moreover, the direction of the keto–enol equilibrium is...
4.2K