The formation of protein aggregates within cells can lead to many pathologic
states ranging from Alzheimer's, Parkinson's, and Huntington's disease, amyotrophic lateral
sclerosis, Lewy-body dementia to frontotemporal dementia. As these protein aggregates
typically appear years before the onset of symptoms, they offer a path to an early diagnosis
and treatment of disease. Detection of these aggregates can be achieved with fluorescent
molecular probes, which function on the principle of push-pull electron systems. With this
in mind, three fluorescent molecular probes with the enaminone moiety were synthesized.
The enaminones were prepared with the reaction of the enol tautomer of the acetyl group
with N,N-dimethylformamide diethyl acetal or N,N-dimethylformamide dimethyl acetal.
All three probes were successfully synthesized and characterised with 1H, 13C NMR and IR
spectroscopy, high resolution mass spectrometry (HRMS) and melting point
measurements. The purity of the probes was proved by high-pressure liquid
chromatography (HPLC). Also, the optical properties of the probes such as absorption,
emission, and excitation were examined. Lastly, these probes were tested for their ability
of aggregate detection. As our experimental model, the TDP-43 protein, associated with
the amyotrophic lateral sclerosis (ALS) patients, was used. Our TDP-43 had a C-terminal
fusion partner maltose binding protein (MBP), which allowed induction of aggregation with
the addition of tobacco etch virus protease (TEV). It was shown that all three synthesised
probes are able to differentiate between the soluble and aggregated form of TDP-43.
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