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Two-site binding of beta-cyclodextrin to the Alzheimer Abeta(1-40) peptide measured with combined PFG-NMR diffusion and induced chemical shifts.

Abstract：

:The interactions of Alzheimer's amyloid beta-peptide with cyclodextrins were studied by (1)H NMR: the translational diffusion coefficient of the peptide and chemical shift changes were studied by the presence of variable concentrations of cyclodextrins. For the full-length peptide, Abeta(1-40), the combined results of translational diffusion and chemical shift changes are consistent with a model where aromatic side chains interact with beta-cyclodextrin with dissociation constants in the millimolar range. The diffusion data were consistent with two beta-cyclodextrin molecules bound per peptide. The binding occurs at two sites, at F(19) and/or F(20) and at Y(10), with dissociation constants K(d)(F) = 4.7 mM and K(d)(Y) = 6.6 mM, respectively, in 10 mM sodium phosphate, pH 7.4 and 298 K. Shorter Alzheimer peptide fragments were studied to measure specific affinities for different binding sites. The N-terminal fragment Abeta(1-9) with a putative binding site at F(4) does not show measurable affinity for beta-cyclodextrin. The fragment Abeta(12-28) has similar apparent affinity (K(d) = 3.8 mM) to beta-cyclodextrin as the full-length peptide Abeta(1-40). Here, the diffusion data suggests a one-to-one stoichiometry, and the binding site is F(19) and/or F(20). Both diffusion results and chemical shift changes give the same affinity. A variant Abeta(12-28)G(19)G(20) without phenylalanines does not bind to beta-cyclodextrin. Other potential ligands, alpha-cyclodextrin, gamma-cyclodextrin, nicotine, and nornicotine do not bind to the Abeta(12-28) fragment. This study shows that combined (1)H NMR diffusion and chemical shift changes may be used to quantitatively determine affinities and stoichiometries of weak interactions, using unlabeled ligands and hosts of comparable sizes.

journal_name

Biochemistry

journal_title

Biochemistry

authors

Danielsson J,Jarvet J,Damberg P,Gräslund A

doi

10.1021/bi036254p

subject

Has Abstract

pub_date

2004-05-25 00:00:00

pages

6261-9

issue

eissn

0006-2960

issn

1520-4995

journal_volume

pub_type

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Two-site binding of beta-cyclodextrin to the Alzheimer Abeta(1-40) peptide measured with combined PFG-NMR diffusion and induced chemical shifts.