Self-association of beta-amyloid peptide (1-40) in solution and binding to lipid membranes

Terzi, E. and Holzemann, G. and Seelig, J.. (1995) Self-association of beta-amyloid peptide (1-40) in solution and binding to lipid membranes. Journal of molecular biology, Vol. 252, H. 5. pp. 633-642.

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Official URL: http://edoc.unibas.ch/dok/A5257445

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The beta-amyloid peptide (beta AP), a 39 to 43 residue peptide, is the major component of Alzheimer plaques. Using circular dichroism spectroscopy, titration calorimetry, and analytical ultracentrifugation we have analyzed the self-association of beta AP(1-40) in aqueous solution and the binding of beta AP(1-40) to negatively charged lipid vesicles. The CD spectra of both aggregation and membrane binding are characterized by an isodichroic point at 212 nm, indicating a simple two-state equilibrium for both cases. In aqueous solution beta AP(1-40) exhibits a reversible, concentration-dependent random coilbeta-structure transition which can be described by a cooperative aggregation model with an association constant of s = 1.05 x 10(4)M-1 and a nucleation parameter of sigma = 0.012. A similar conformational change is observed upon addition of lipid. At a given peptide concentration, the addition of negatively charged, small unilamellar vesicles also induces a conformational change from a random coil conformation to a conformation with 40 to 60% beta-structure. The binding isotherm can be measured with high sensitivity titration calorimetry. It is approximately linear in the initial binding phase and exhibits an apparent saturation behaviour. The apparent binding constant decreases with concentration from Kapp approximately 2100 M-1 at low concentration to 700 M-1 at the highest concentration measured. Peptide penetration into the lipid membrane and peptide aggregation at the membrane surface are proposed as possible mechanisms to explain the lipid-induced random coilbeta-structure transition.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Biophysical Chemistry (Seelig J)
UniBasel Contributors:Seelig, Joachim
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:22 Mar 2012 14:19
Deposited On:22 Mar 2012 13:18

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