Common Benzothiazole and Benzoxazole Fluorescent DNA Intercalators for Studying Alzheimer Aβ _1-42 and Prion Amyloid Peptides

Abstract

Amyloids are fibrillar protein aggregates associated with a number of neurodegenerative pathologies including Alzheimer and Creutzfeldt-Jakob disease. The study of amyloids is usually based on fluorescence with the dye thioflavin-T. Although a number of amyloid binding compounds have been synthesized, many are nonfluorescent or not readily available for research use. Here we report on a class of commercial benzothiazole/benzoxazole containing fluorescent DNA intercalators from Invitrogen that possess the ability to bind amyloid Aβ1-42 peptide and hamster prion. These dyes fluoresce from 500-750 nm and are available as dimers or monomers. We demonstrate that these dyes can be used as acceptors for thioflavin-T fluorescence resonance energy transfer as well as reporter groups for binding studies with Congo red and chrysamine G. As more potential therapeutic compounds for these diseases are generated, there is a need for simple and inexpensive methods to monitor their interactions with amyloids. The fluorescent dyes reported here are readily available and can be used as tools for biochemical studies of amyloid structures and in vitro screening of potential therapeutics.

Substoichiometric molecular control and amplification of the initiation and nature of amyloid fibril formation: lessons from and for blood clotting

“…In an interesting development, Stefansson and colleagues [239] noted that (i) the thiazole moiety is critical to binding [201], and (ii) that a number of modern, sensitive DNA-intercalating dyes also contain the thiazole nucleus. They showed [239] that these dyes too would bind to β-amyloid fibrils, albeit not normally (but cf. [240]) with quite with the same fluorescence enhancement as shown by…”

Dual Functional Small Molecule Probes as Fluorophore and Ligand for Misfolding Proteins

“…Recently, Stefansson et al . reported that the fluorescent intensity of benzothiazole and benzoxazole dimers could increase several folds when the dyes were incubated with Hamster prion proteins [119]. Bresjanac et al .…”

DNA intercalators as amyloid assembly modulators: mechanistic insights

“…22,23 Consequently, various planar molecules/compounds/drugs which are known to interact and modulate DNA structure have been tested for their anti-amyloidogenic potential. [24][25][26] The best known drugs of this class included two FDA approved DNA intercalators, 4 0 -iodo-4 0 -deoxydoxorubicin for systemic amyloidosis 27,28 and mitoxantrone/picoxantrone against Ab brillation. 29,30 Traditionally, these compounds comprise simple class of planar organic molecules capable of modulating genetic and epigenetic expression via stacking in between adjacent base pairs of DNA.…”

“…However, inhibition by EGCG by virtue of its hydrophobic/H-bond interactions requires thorough investigation behind its mechanism of action. To comprehensively understand the role of hetero-aromatic associations to interfere with the amyloidogenic pathways, we designed this current study by employing the pre-brillar structural coordinates of IAP amyloid-core containing sequence (NFGAILS), IAP (22)(23)(24)(25)(26)(27)(28) as our model system (Fig. 1).…”

“…1). The choice of this system serves dual advantages in terms of Phe-23 mediated assembly formation 18,38 and in pre-availability of atomic coordinates of supramolecular amyloid assembly of IAP (22)(23)(24)(25)(26)(27)(28). 39 Thus, the entire reaction pathway for IAP (22)(23)(24)(25)(26)(27)(28) aggregation and in process interference mechanisms by planar compounds can be mapped though strategic simulation of its aggregation pathway.…”