Investigation of the Mechanism of β-Amyloid Fibril Formation by Kinetic and Thermodynamic Analyses
Extracellular β-amyloid (Aβ) deposit is considered as one of the primary factors that induce Alzheimer’s disease (AD). The effects of various environmental factors, including temperature, ionic strength, and pH, on Aβ (1–40) aggregation mechanisms were investigated in this study by spectrometry, iso...
Saved in:
Published in | Langmuir Vol. 24; no. 11; pp. 5802 - 5808 |
---|---|
Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Washington, DC
American Chemical Society
03.06.2008
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Extracellular β-amyloid (Aβ) deposit is considered as one of the primary factors that induce Alzheimer’s disease (AD). The effects of various environmental factors, including temperature, ionic strength, and pH, on Aβ (1–40) aggregation mechanisms were investigated in this study by spectrometry, isothermal titration calorimetry (ITC), and hydrophobic fluorescence assay. In the aggregation process, the secondary structure of Aβ (1–40) transforms to the β-sheet conformation, which could be described as a two-state model. As the temperature and ionic strength increase, the conformation of Aβ converts to the β-sheet structure with an increased rate. Results of circular dichroism monitoring demonstrate that the rate constant of nucleation is smaller than that of elongation, and the nucleation is the rate-determining step during the overall Aβ aggregation. The β-sheet structure was stabilized by hydrophobic forces, as revealed by the ITC measurements. The different structural aggregates and forming pathways could be identified and discriminated at high and low ionic strengths, resulting in distinctive fibril conformations. Furthermore, the thermodynamic analysis shows that hydrophobic interaction is the major driving force in the nucleation step. Our study provides an insight into the discriminative mechanisms of β-amyloid aggregation via kinetics and thermodynamics, especially the first reported thermodynamics information obtained by ITC. |
---|---|
Bibliography: | istex:1E5217F686BB3E9A532606130095F7480B8DCB38 ark:/67375/TPS-B3KFXK20-J ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0743-7463 1520-5827 |
DOI: | 10.1021/la703369b |