Fluorescent N-arylaminonaphthalene sulfonate probes for amyloid aggregation of α-synuclein,

SOLEDAD CELEJ, ELIZABETH JARES-ERIJMAN, THOMAS JOVIN

BIOPHYSICAL JOURNAL

Año: 2007 vol. 94

0006-3495

The deposition of fibrillar structures (amyloids) is characteristic of pathological conditions including Alzheimer´s and Parkinson´s (PD) diseases. The detection of protein deposits and the evaluation of their kinetics of aggregation are generally based on fluorescent probes such as Thioflavin T and Congo Red. In a search for improved fluorescence tools for studying amyloid formation, we explored the ability of N-arylaminonaphthalene sulfonate (NAS) derivatives to act as noncovalent probes of -synuclein (AS) fibrillation, a process linked to PD and other neurodegenerative disorders. The compounds bound to fibrillar AS with µM Kds, and exhibited fluorescence enhancement, hyperchromism, and high anisotropy. We conclude that the probes experience a hydrophobic environment and/or restricted motion in a polar region. Time- and spectrally-resolved emission intensity and anisotropy provided further information regarding structural features of the protein and the dynamics of solvent relaxation. The steady-state and time-resolved parameters changed during the course of aggregation. Compared with Thioflavin T, NAS derivatives constitute more sensitive and versatile probes for AS aggregation detecting, in the case of the bis-NAS, oligomeric as well as fibrillar species. They may function in convenient, continuous assays, thereby providing useful tools for studying the mechanisms of amyloid formation and for high throughput screening of factors inhibiting and/or reversing protein aggregation in neurodegenerative diseases.