Related Experiment Video
Updated: May 29, 2026
06:06
In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
Zinc(II) complexes of ubiquitin: speciation, affinity and binding features
Giuseppe Arena1, Roberto Fattorusso, Giuseppe Grasso
1Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Viale A. Doria 6, 95125 Catania, Italy.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|September 29, 2011
Summary
Zinc(II) ions bind to ubiquitin, promoting protein self-assembly and potentially contributing to neurodegeneration. This study details zinc binding sites and their impact on ubiquitin
Area of Science:
- Biochemistry
- Neuroscience
- Metalloprotein studies
Background:
- Intraneuronal inclusions of hypermetallated, ubiquitinated proteins are linked to neurodegeneration.
- The role of metal ions in ubiquitin-proteasome system dysfunction requires further investigation.
Purpose of the Study:
- To investigate zinc(II)/ubiquitin binding interactions.
- To determine the effects of zinc(II) on ubiquitin stability and self-assembly.
Main Methods:
- Potentiometric titrations to determine zinc(II)/ubiquitin speciation and affinity.
- NMR DOSY experiments to assess changes in ubiquitin diffusion upon zinc(II) addition.
- Chemical shift perturbation studies to map zinc(II) binding sites on ubiquitin.
- Differential scanning calorimetry to evaluate the impact of zinc(II) on protein thermal stability.
Main Results:
- At neutral pH, zinc(II) forms ZnUb and Zn(2)Ub species with ubiquitin.
- NMR data indicate zinc(II) promotes ubiquitin self-assembly.
- Two distinct zinc(II) binding modes were identified on ubiquitin, one involving known copper-binding regions and another domain, and a looser site at His68.
- Zinc(II) binding did not alter ubiquitin's thermal stability but influenced its self-association propensity.
Conclusions:
- Zinc(II) ions interact with specific sites on ubiquitin.
- These interactions promote ubiquitin self-association, potentially contributing to the formation of inclusions observed in neurodegenerative diseases.
More Related Videos
Related Concept Videos
01:57Protein Complexes with Interchangeable Parts
Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex’s function. Often some of the proteins in the complex can be replaced by a closely related variant to give a complex that contains many of the same components yet is functionally distinct.
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
02:04Covalently Linked Protein Regulators
Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.
These groups modify specific amino acids in a protein.
01:09Complexation Equilibria: Factors Influencing Stability of Complexes
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...
01:19Complexation Equilibria: The Chelate Effect
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
00:49Ligand Binding and Linkage
Allosteric proteins have more than one ligand binding site; the binding of a ligand to any of these sites influences the binding of ligands to the other sites. When a protein is allosteric, its binding sites are called coupled or linked. In the case of enzymes, the site that binds to the substrate is known as the active site and the other site is known as the regulatory site. When a ligand binds to the regulatory site, this leads to conformational changes in the protein that can influence the...
00:43Complexometric Titration: Ligands
Different monodentate and polydentate ligands are used as complexing agents in complexometric titration reactions. The formation of complexes by mono- and bidentate ligands involves two or more intermediate steps, limiting their use as complexing agents. In comparison, polydentate ligands can form complexes with metal ions in a single-step process, facilitating sharper end points. This means polydentate ligands, such as amino carboxylic acid derivatives, are most commonly employed in...