Related Experiment Video
Updated: Jun 25, 2026
08:53
Characterization of pH-Dependent Reversible Self-Assembly of Amyloid Beta 1-40-Coated Gold Colloids
Published on: March 21, 2025
A kinetic model for beta-amyloid adsorption at the air/solution interface and its implication to the beta-amyloid
Dianlu Jiang1, Kim Lien Dinh, Travis C Ruthenburg
1Department of Chemistry and Biochemistry, California State University, Los Angeles, Los Angeles, California 90032, USA.
The Journal of Physical Chemistry. B
|March 6, 2009
Summary
Amyloid beta (Abeta) peptide adsorption at interfaces, even at low concentrations, involves a lag phase and conformational changes to alpha-helical structures. This suggests misfolding may precede adsorption, explaining in vivo fibrillation.
Area of Science:
- Biochemistry
- Physical Chemistry
- Materials Science
Background:
- Amyloid beta (Abeta) peptide aggregation is implicated in neurodegenerative diseases.
- In vitro studies typically use high Abeta concentrations, differing from physiological conditions.
Purpose of the Study:
- To investigate the adsorption kinetics of Abeta(1-42) at the air/buffer interface at low, physiologically relevant concentrations.
- To elucidate the conformational changes and kinetic mechanisms governing Abeta adsorption.
Main Methods:
- Langmuir-Blodgett trough for adsorption studies.
- Attenuated total reflection-infrared (ATR-IR) spectroscopy.
- Circular dichroism (CD) spectroscopy.
Main Results:
- Adsorption exhibited a concentration and temperature-dependent lag phase.
- A high activation energy (62.2 +/- 4.1 KJ/mol) and a rate constant proportional to bulk Abeta concentration were determined.
- Natively unstructured Abeta underwent a conformational change to alpha-helical structures near the interface.
Conclusions:
- Abeta adsorption is kinetically controlled, with misfolding and conformational changes occurring prior to adsorption.
- Interfaces like cell membranes may facilitate Abeta aggregation by promoting initial misfolding and accumulation.
- This model explains in vivo Abeta fibrillation at nanomolar concentrations and has broader applications for biomolecule adsorption studies.
Related Concept Videos
03:03Amyloid Fibrils
Amyloid fibrils are aggregates of misfolded proteins. Under most circumstances, misfolded proteins are either refolded by chaperone proteins or degraded by the proteasome. However, in the case of a mutation or a disease, these proteins can accumulate to form large clusters and often further assemble to form elongated fibers, called fibrils.
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
03:03Amyloid Fibrils
Amyloid fibrils are aggregates of misfolded proteins. Under most circumstances, misfolded proteins are either refolded by chaperone proteins or degraded by the proteasome. However, in the case of a mutation or a disease, these proteins can accumulate to form large clusters and often further assemble to form elongated fibers, called fibrils.
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
01:25Adsorption Isotherms II
Brunauer, Emmett, and Teller (BET) introduced a theory in 1938 that modified Langmuir's assumptions to explain multilayer physical adsorption. This theory is applicable to Type II isotherms and provides a more realistic picture of adsorption processes. The BET theory assumes a uniform solid surface with localized adsorption sites, where adsorption at one site doesn't affect adsorption at neighboring sites. This theory also allows for the possibility of additional molecules being adsorbed on top...
01:58Cooperative Allosteric Transitions
Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand binds to any of these subunits, it triggers a conformational change that affects the binding sites in the other subunits; this can change the affinity of the other sites for their respective ligands. The ability of the protein to change the shape of its binding site is attributed to the presence of a mix of flexible and stable segments in the...
01:15Antifungal Agents
Amphotericin B is a broad-spectrum antifungal agent that exploits structural differences between fungal and mammalian cell membranes. Its amphipathic structure—featuring a hydrophobic polyene-lactone ring and a hydrophilic region containing mycosamine and carboxylic acid groups—enables selective binding to ergosterol, a sterol predominantly found in fungal plasma membranes. This selective interaction underlies the drug’s antifungal activity, although weak binding to cholesterol contributes to...