Fluorescent Probe DCVJ Shows High Sensitivity for Characterization of Amyloid ?-Peptide Early in the Lag Phase.

ABSTRACT: The aggregation of intrinsically disordered and misfolded proteins in the form of oligomers and fibrils plays a crucial role in a number of neurological and neurodegenerative diseases. Currently, most probes and biophysical techniques that detect and characterize fibrils at high resolution fail to show sensitivity and binding for oligomers. Here, we show that 9-(dicyano-vinyl)julolidine (DCVJ), a class of molecular rotor, binds amyloid beta (A?) early aggregates, and we report the kinetics as well as packing of the oligomer formation. The binding of DCVJ to A?40 increased its emission intensity with time at 510?nm and produced a second excimer peak at 575?nm. However, DCVJ did not bind to the prefibrillar aggregates of A?42, which indicated that the oligomers formed by A?40 and A?42 were not the same. The F4C F19W mutant of A?40, which did not form fibrils, also bound DCVJ, but the emission spectral profile varied from that of the wild-type (WT). Atomic force microscopy images of WT A?40, the F4C F19W mutant, and A?42 oligomers displayed differences in size and shape, confirming the difference in their DCVJ spectra. The effect of epigallocatechin-3-gallate (EGCG) on the reduction of A?42 fibrils was also observed with finer detail than with other techniques. The results of this study show that DCVJ detects early aggregates and provides valuable information regarding the oligomer kinetics, packing, and mechanism of formation.

SUBMITTER: Nagarajan S 

PROVIDER: S-EPMC5806135 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature