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A Novel Tool to Investigate the Early and Late Stages of α‑Synuclein Aggregation
journal contribution
posted on 2020-05-14, 16:16 authored by Sumanta Ghosh, Sakshi, Bikash Chandra Swain, Ritobrita Chakraborty, Umakanta Tripathy, Krishnananda ChattopadhyayThe accumulation
of an inherently disordered protein α-synuclein
(α-syn) aggregates in brain tissue play a pivotal role in the
pathology and etiology of Parkinson’s disease. Aggregation
of α-syn has been found to be complex and heterogeneous, occurring
through multitudes of early- and late-stage intermediates. Because
of the inherent complexity and large dynamic range (between a few
microseconds to several days under in vitro measurement conditions),
it is difficult for the conventional biophysical and biochemical techniques
to sample the entire time window of α-syn aggregation. Here,
for the first time, we introduced the Z-scan technique as a novel
tool to investigate different conformations formed in the early and
late stage of temperature and mechanical stress-induced α-syn
aggregation, in which different species showed its characteristic
nonlinear characteristics. A power-dependent study was also performed
to observe the changes in the protein nonlinearity. The perceived
nonlinearity was accredited to the thermal-lensing effect. A switch
in the sign of the refractive nonlinearity was observed for the first
time as a signature of the late oligomeric conformation, a prime suspect
that triggers cell death associated with neurodegeneration. We validate
Z-scan results using a combination of different techniques, like thioflavin-T
fluorescence assay, fluorescence correlation spectroscopy, Fourier-transform
infrared spectroscopy, and atomic force microscopy. We believe that
this simple, inexpensive, and sensitive method can have potential
future applications in detecting/monitoring conformations in other
essential peptides/proteins related to different neurodegenerative
and other human diseases.
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fluorescence correlation spectroscopytriggers cell deathNovel ToolZ-scan techniquefuture applicationsbrain tissueZ-scan resultstime windowα- synnovel toolpower-dependent studyAggregationthioflavin-T fluorescence assayα- syn aggregationnonlinear characteristicslate-stage intermediatesstress-induced α- syn aggregationforce microscopyoligomeric conformationprotein nonlinearitythermal-lensing effect
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