Related Experiment Video
Updated: May 20, 2026
12:08
Monitoring the Reductive and Oxidative Half-Reactions of a Flavin-Dependent Monooxygenase using Stopped-Flow Spectrophotometry
Published on: March 18, 2012
Cofactor binding protects flavodoxin against oxidative stress.
Simon Lindhoud1, Willy A M van den Berg, Robert H H van den Heuvel
1Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands.
Plos One
|July 26, 2012
Summary
Cofactor binding protects proteins from oxidative damage. Flavin mononucleotide (FMN) binding stabilizes Azotobacter vinelandii flavodoxin, preventing cysteine oxidation and modification.
Area of Science:
- Biochemistry
- Protein Chemistry
- Oxidative Stress Biology
Background:
- Organisms possess protective mechanisms against protein oxidative damage.
- Flavodoxin is a protein involved in redox reactions.
- Oxidative stress can lead to protein modification and dysfunction.
Purpose of the Study:
- To investigate the role of cofactor binding in protecting proteins against oxidative damage.
- To identify specific mechanisms by which flavin mononucleotide (FMN) protects Azotobacter vinelandii flavodoxin.
- To characterize the oxidation states of a key cysteine residue (Cys69) in flavodoxin.
Main Methods:
- Protein oxidation assays using hydrogen peroxide.
- Identification of oxidation-sensitive cysteine residues.
- Chemical modification studies using 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl).
- Reversal studies using dithiothreitol (DTT).
Main Results:
- Flavin mononucleotide (FMN) protects Azotobacter vinelandii flavodoxin from hydrogen peroxide-induced oxidation.
- Cys69 is an oxidation-sensitive residue located near the FMN binding site.
- Oxidative stress induces dimerization of apoflavodoxin and formation of sulfinate and sulfonate states of Cys69.
- Sulfenic acid is a transient intermediate, while sulfinate and sulfonate forms are irreversible.
- Bound flavin enhances protein stability and protects against irreversible oxidation and thiol modification.
Conclusions:
- Cofactor binding is a significant protective mechanism against protein oxidation.
- FMN binding to flavodoxin confers substantial stability and prevents irreversible oxidative damage to Cys69.
- These findings highlight the dual role of cofactors in protein function and protection.
More Related Videos
12:41Application of an In vitro DNA Protection Assay to Visualize Stress Mediation Properties of the Dps Protein
Published on: May 31, 2013
04:32Extraction of Cofactor F420 for Analysis of Polyglutamate Tail Length from Methanogenic Pure Cultures and Environmental Samples
Published on: October 14, 2021
Related Concept Videos
01:17Oxidation of Phenols to Quinones
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 property is crucial in...
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 property is crucial in...
01:29Role of Reduced Coenzymes NADH and FADH₂
The energy released from the breakdown of the chemical bonds within nutrients can be stored either through the reduction of electron carriers or in the bonds of adenosine triphosphate (ATP). In living systems, a small class of compounds functions as mobile electron carriers, molecules that bind to and shuttle high-energy electrons between compounds in pathways. The principal electron carriers that will be considered originate from the B vitamin group and are derivatives of nucleotides; they are...
01:24Cofactors and Coenzymes
Enzymes are proteins made of amino acids. The functional group of each constituent amino acid catalyzes a wide variety of chemical reactions via ionic interactions or acid-base reactions. However, amino acids cannot catalyze oxidation-reduction and group transfer reactions and need to be aided by non-protein components called cofactors. Cofactors are also referred to as the chemical teeth of an enzyme.
Cofactors can be metallic ions or organic molecules called coenzymes. These types of helper...
Cofactors can be metallic ions or organic molecules called coenzymes. These types of helper...
01:27Cofactors and Coenzymes
Enzymes require additional components for proper function. There are two such classes of molecules: cofactors and coenzymes. Cofactors are metallic ions and coenzymes are non-protein organic molecules. Both of these types of helper molecule can be tightly bound to the enzyme or bound only when the substrate binds.
01:27Cofactors and Coenzymes
Enzymes require additional components for proper function. There are two such classes of molecules: cofactors and coenzymes. Cofactors are metallic ions and coenzymes are non-protein organic molecules. Both of these types of helper molecule can be tightly bound to the enzyme or bound only when the substrate binds.
03:00Molecular Chaperones and Protein Folding
The native conformation of a protein is formed by interactions between the side chains of its constituent amino acids. When the amino acids cannot form these interactions, the protein cannot fold by itself and needs chaperones. Notably, chaperones do not relay any additional information required for the folding of polypeptides; the native conformation of a protein is determined solely by its amino acid sequence. Chaperones catalyze protein folding without being a part of the folded protein.
The...
The...