Related Experiment Video
Updated: Aug 13, 2026
10:24
Defining Hsp33's Redox-regulated Chaperone Activity and Mapping Conformational Changes on Hsp33 Using Hydrogen-deuterium Exchange Mass Spectrometry
Published on: June 7, 2018
Peroxynitrite-induced structural remodeling and aggregation of hemoglobin under nitroxidative stress
Shaik Basha1, Aradhika Vijeev1, Darshan Chikkanayakanahalli Mukunda1,2
1Department of Biophysics, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal, India.
Protein Science : a Publication of the Protein Society
|August 12, 2026
Summary
Peroxynitrite (PN) causes hemoglobin (Hb) to aggregate into amorphous structures, not amyloid fibrils. This nitroxidative damage impacts protein stability and disease pathways.
Area of Science:
- Biochemistry
- Biophysics
- Proteomics
Background:
- Peroxynitrite (PN), a reactive nitrogen species (RNS), contributes to protein damage in diseases.
- Hemoglobin (Hb) is a target of PN, but its structural changes and aggregation are not well understood.
Purpose of the Study:
- To investigate the structural remodeling and aggregation of human hemoglobin (Hb) induced by controlled peroxynitrite (PN) exposure.
- To define the physicochemical thresholds governing PN-induced Hb structural changes and aggregation.
Main Methods:
- Human Hb was exposed to varying PN concentrations.
- Characterization involved fluorescence spectroscopy, UV-vis spectroscopy, carbonyl assays, Thioflavin T (ThT), Congo Red (CR), FTIR, DLS, XRPD, SEM, AFM, and fluorescence microscopy.
Main Results:
- Low PN concentrations caused heme oxidation and aromatic residue modification.
- Higher PN concentrations led to α-helix loss, β-sheet gain, surface charge neutralization, and increased size.
- Hb formed amorphous, oligomeric aggregates, not amyloid fibrils, with PN accelerating thermal aggregation.
Conclusions:
- PN induces Hb structural destabilization and amorphous aggregation, distinct from amyloid fibrillation.
- Physicochemical thresholds differentiate protective scavenging from damaging aggregation.
- Findings provide a framework for understanding nitroxidative protein aggregation in disease.
Related Concept Videos
01:28Protein Denaturation
The function of proteins depends on their native three-dimensional structure, which is dictated by the amino acid sequence of the specific protein. Folding of the polypeptide chain takes place under specific conditions that energetically favor the folded conformation. In contrast, protein denaturation occurs spontaneously under unfavorable conditions that disrupt the integrity of the folded conformation. Thus, the chemical and physical environment of a protein, such as significant changes in pH...
01:24Hemoglobin
Hemoglobin is a globular protein made up of four subunits. Two of these subunits are alpha chains, and the other two are beta chains. Each subunit contains a molecule of heme, which has an iron atom and can bind to oxygen. When an oxygen molecule binds to one heme group, it changes the shape of hemoglobin, making it easier for the other heme groups to bind oxygen as well.
When all four heme groups are bound to oxygen, the resulting molecule is called oxyhemoglobin. As a result, arterial blood...
When all four heme groups are bound to oxygen, the resulting molecule is called oxyhemoglobin. As a result, arterial blood...
01:27Oxygen Transport in the Blood
Hemoglobin (Hb) is a crucial molecule in the human body, consisting of four polypeptide chains, each bound to an iron-containing heme group. This unique structure enables hemoglobin to bind to oxygen, with each molecule capable of combining with four molecules of oxygen, leading to rapid and reversible oxygen loading. When fully loaded with oxygen, it is called oxyhemoglobin, while hemoglobin that has released oxygen is called reduced hemoglobin or deoxyhemoglobin. As hemoglobin binds oxygen,...
01:23Hypoxia
Hypoxia is a medical condition characterized by an inadequate oxygen supply to body tissues. It typically manifests as a bluish discoloration of the skin and mucosae, especially in fair-skinned individuals, when hemoglobin (Hb) saturation drops below 75%.
Types of Hypoxia
There are four primary types of hypoxia, each resulting from a different cause:
1. Anemic hypoxia: This type occurs due to insufficient oxygen delivery caused by a lack of red blood cells (RBCs) or RBCs with abnormal or...
Types of Hypoxia
There are four primary types of hypoxia, each resulting from a different cause:
1. Anemic hypoxia: This type occurs due to insufficient oxygen delivery caused by a lack of red blood cells (RBCs) or RBCs with abnormal or...
01:26Protein Modifications in the RER
Modification of secretory and transmembrane proteins entering the rough ER begins in the ER lumen. These modifications aid in protein folding and stabilize the acquired tertiary structure. Protein modifications in the rough ER co-occur at different stages of protein folding.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
01:25Bioactivation and Tissue Toxicity
Bioactivation is a metabolic process that transforms less reactive substances into highly reactive metabolites, initiating tissue toxicity. This transformation can lead to various toxic effects, including carcinogenesis and teratogenesis. Reactive metabolites are classified into two main types: electrophiles and free radicals.Electrophiles are electron-deficient species and are produced primarily by the enzyme cytochrome P-450 during the metabolism of compounds containing carbon, nitrogen, or...