Pinacyanol as effective probe of fibrillar β-amyloid peptide: Comparative study with Congo Red

✍ Scribed by Raimon Sabaté; Joan Estelrich

• Book ID: 101712796
• Publisher: Wiley (John Wiley & Sons)
• Year: 2003
• Tongue: English
• Weight: 138 KB
• Volume: 72
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.10485

✦ Synopsis

Abstract

The binding of pinacyanol (PIN), a cationic cyanine dye, to β‐amyloid fibrils (Aβ), which are associated with Alzheimer disease, was quantified by absorption spectrophotometry to measure the concentration of PIN bound to Aβ as a function of the Aβ concentration or by means of the separation of free PIN from bound PIN by centrifugation and subsequent analysis of the supernatant by visible‐absorption spectrophotometry. Both methods gave equivalent results. The stoichiometry of PIN binding to Aβ was 1, and the curve representing the concentration effect of Aβ on the concentration of a dye–Aβ complex showed a biphasic curve instead of the hyperbolic curve that is characteristic of weak ligand–macromolecule interactions [e.g., as shown by Congo Red (CR)]). This and the fact that a Scatchard plot could not be fitted to the experimental data suggested that PIN binds tightly to Aβ. A comparison to the interaction of CR with Aβ led us to conclude that PIN is more sensitive than CR. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy), 2003