Related Experiment Video

Updated: Sep 16, 2026

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR
14:44

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR

Published on: December 16, 2013

The role of histidines 26 and 33 in the structural stabilization of cytochrome c

W Qin1, R Sanishvili, B Plotkin

  • 1Department of Biological Sciences, University of Illinois at Chicago 60607, USA.

Biochimica Et Biophysica Acta
|September 27, 1995
PubMed

Insights

Investigating rat cytochrome c, this study used mutagenesis to understand how non-heme histidines (His-26, His-33) impact protein stability. Mutations revealed His-26 is crucial for local and global stability, while His-33 enhances stability through hydrophobic interactions.

Area of Science:

  • Biochemistry
  • Protein Science
  • Molecular Biology

Background:

  • Cytochrome c is a vital protein involved in cellular respiration and apoptosis.
  • Non-heme coordinating histidines play roles in protein structure and function.
  • Understanding protein stability is crucial for comprehending biological processes.

Purpose of the Study:

  • To investigate the roles of non-heme histidines (His-26 and His-33) in rat cytochrome c stability.
  • To elucidate the structural and functional consequences of specific histidine mutations.
  • To determine the impact of these mutations on the Met-80 sulfur to heme iron bond and overall protein stability.

Main Methods:

  • Site-directed mutagenesis was employed to create specific histidine substitutions (His-26 to Val, His-33 to Phe, Asn-52 to Ile).
  • Protein stability was assessed by measuring resistance to unfolding in urea solutions.
  • The integrity of the Met-80 sulfur to heme iron bond was evaluated under varying pH and temperature conditions.

Main Results:

  • Substitution of His-26 with Valine decreased both local and global protein stability, likely due to loss of hydrogen bonds and increased internal hydration.
  • Mutation of Asn-52 to Isoleucine fully restored the sulfur-iron bond stability and partially restored global stability.
  • Replacing His-33 with Phenylalanine increased global stability via hydrophobic interactions, and this mutation could partially counteract the destabilizing effects of the His-26 to Val substitution.

Conclusions:

  • His-26 is critical for maintaining the local and global stability of rat cytochrome c.
  • His-33 contributes to protein stability through hydrophobic interactions, influencing the protein's structural integrity.
  • Specific mutations can differentially affect local (sulfur-iron bond) and global protein stability, highlighting the complex interplay of residues in protein structure.

More Related Videos

Sedimentation Equilibrium of a Small Oligomer-forming Membrane Protein: Effect of Histidine Protonation on Pentameric Stability09:49

Sedimentation Equilibrium of a Small Oligomer-forming Membrane Protein: Effect of Histidine Protonation on Pentameric Stability

Published on: April 2, 2015

Defining Hsp33's Redox-regulated Chaperone Activity and Mapping Conformational Changes on Hsp33 Using Hydrogen-deuterium Exchange Mass Spectrometry10:24

Defining Hsp33's Redox-regulated Chaperone Activity and Mapping Conformational Changes on Hsp33 Using Hydrogen-deuterium Exchange Mass Spectrometry

Published on: June 7, 2018

Related Concept Videos

Protein Folding01:49

Protein Folding

Proteins are chains of amino acids linked together by peptide bonds. Upon synthesis, a protein folds into a three-dimensional conformation which is critical to its biological function. Interactions between its constituent amino acids guide protein folding, and hence the protein structure is primarily dependent on its amino acid sequence.Protein Structure Is Critical to Its Biological FunctionProteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
Gene Families01:57

Gene Families

Gene families consist of groups of genes proposed to have originated from a common ancestor. Typically these arise through events in which a gene or genes are mistakenly duplicated during cell division. Unlike their parent genes (which are subject to selection pressure to maintain function), these gene copies do not need to preserve their sequences and may evolve at a relatively faster rate.
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
Histone Variants at the Centromere02:30

Histone Variants at the Centromere

Histone variants are the histone proteins with structural and sequence variations. These variants may be regarded as “mutant” forms that replace their canonical histone counterparts in the nucleosomes. Specific post-translational modifications on the histone variants enable further chromatin complexity and regulate tissue-specific gene expression. The most common histone variants are from histone H2A, H2B, and linker histone H1 families. However, several variants of histone H3 variants are also...
The Supercomplexes in the Crista Membrane01:41

The Supercomplexes in the Crista Membrane

The mitochondrial cristae membrane is the primary site for the oxidative phosphorylation (OXPHOS) process of energy conversion mediated through respiratory complexes I to V. These complexes have been widely studied for decades, and it has been proven that they form supramolecular structures called respiratory supercomplexes (SC). These higher-order complexes may be crucial in maintaining the biochemical structure and improving the physiological activity of the individual complexes while...
Protein Folding01:25

Protein Folding

Proteins are chains of amino acids linked together by peptide bonds. Upon synthesis, a protein folds into a three-dimensional conformation, critical to its biological function. Interactions between its constituent amino acids guide protein folding, and hence the protein structure is primarily dependent on its amino acid sequence.
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
Electron Transport Chain: Complex III and IV01:43

Electron Transport Chain: Complex III and IV

During the electron transport chain, electrons from NADH and FADH2 are first transferred to complexes I and II, respectively. These two complexes then transfer the electrons to ubiquinol, which carries them further to complex III. Complex III passes the electrons across the intermembrane space to Cyt c, which carries them further to complex IV. Complex IV donates electrons to oxygen and reduces it to water. As electrons pass through complexes I, III, and IV, the energy released aids the pumping...