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The structure and protein binding of amyloid-specific dye reagents.

100%

Stopa B., Piekarska B., Konieczny L., Rybarska J., Spólnik P., Zemanek G., Roterman I., Król M.

2003

vol. 50

issue 4

1213-1227

The self-assembling tendency and protein complexation capability of dyes related to Congo red and also some dyes of different structure were compared to explain the mechanism of Congo red binding and the reason for its specific affinity for β-structure. Complexation with proteins was measured directly and expressed as the number of dye molecules bound to heat-aggregated IgG and to two light chains with different structural stability. Binding of dyes to rabbit antibodies was measured indirectly as the enhancement effect of the dye on immune complex formation. Self-assembling was tested using dynamic light scattering to measure the size of the supramolecular assemblies. In general the results show that the supramolecular form of a dye is the main factor determining its complexation capability. Dyes that in their compact supramolecular organization are ribbon-shaped may adhere to polypeptides of β-conformation due to the architectural compatibility in this unique structural form. The optimal fit in complexation seems to depend on two contradictory factors involving, on the one hand, the compactness of the non-covalently stabilized supramolecular ligand, and the dynamic character producing its plasticity on the other. As a result, the highest protein binding capability is shown by dyes with a moderate self-assembling tendency, while those arranging into either very rigid or very unstable supramolecular entities are less able to bind.

Formation of amyloid-like aggregates through the attachment of protein molecules to a Congo red scaffolding framework ordered under the influence of an electric field

81%

Stopa B., Piekarska B., Konieczny L., Król M., Rybarska J., Jagusiak A., Spólnik P., Roterman I., Urbanowicz B., Piwowar P., Lewiński K.

Open Chemistry

2010

vol. 8

issue 1

41-50

This study describes a technique which makes it possible to introduce the amyloid-like order to protein aggregates by using the scaffolding framework built from supramolecular, fibrillar Congo red structures arranged in an electric field. The electric field was used not only to obtain a uniform orientation of the charged dye fibrils, but also to make the fibrils long, compact and rigid due to the delocalization of pi electrons, which favors ring stacking and, as a consequence, results in an increased tendency to self-assemble. The protein molecules (immunoglobulin L chain lambda, ferritin) attached to this easily adsorbing dye framework assume its ordered structure. The complex precipitating as plate-like fragments shows birefringence in polarized light. The parallel organization of fibrils can be observed with an electron microscope. The dye framework may be removed via reduction with sodium dithionite, leaving the aggregated protein molecules in the ordered state, as confirmed by X-ray diffraction studies. [...]

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1 Acta Biochimica Polonica

1 Open Chemistry

1 2010

1 2003

2 Konieczny L.

2 Król M.

2 Piekarska B.

2 Roterman I.

2 Rybarska J.

2 Spólnik P.

2 Stopa B.

1 Jagusiak A.

1 Lewiński K.

1 Piwowar P.

1 Urbanowicz B.

1 Zemanek G.

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The structure and protein binding of amyloid-specific dye reagents.

Formation of amyloid-like aggregates through the attachment of protein molecules to a Congo red scaffolding framework ordered under the influence of an electric field