4 research outputs found
Probing Distinct Fullerene Formation Processes from Carbon Precursors of Different Sizes and Structures
Fullerenes,
cage-structured carbon allotropes, have been the subject
of extensive research as new materials for diverse purposes. Yet,
their formation process is still not clearly understood at the molecular
level. In this study, we performed laser desorption ionization-ion
mobility-mass spectrometry (LDI-IM-MS) of carbon substrates possessing
different molecular sizes and structures to understand the formation
process of fullerene. Our observations show that the formation process
is strongly dependent on the size of the precursor used, with small
precursors yielding small fullerenes and large graphitic precursors
generally yielding larger fullerenes. These results clearly demonstrate
that fullerene formation can proceed via both bottom-up and top-down
processes, with the latter being favored for large precursors and
more efficient at forming fullerenes. Furthermore, we observed that
specific structures of carbon precursors could additionally affect
the relative abundance of C<sub>60</sub> fullerene. Overall, this
study provides an advanced understanding of the mechanistic details
underlying the formation processes of fullerene
Probing Conformational Change of Intrinsically Disordered α‑Synuclein to Helical Structures by Distinctive Regional Interactions with Lipid Membranes
α-Synuclein
(α-Syn) is an intrinsically disordered
protein, whose fibrillar aggregates are associated with the pathogenesis
of Parkinson’s disease. α-Syn associates with lipid membranes
and forms helical structures upon membrane binding. In this study,
we explored the helix formation of α-Syn in solution containing
trifluoroethanol using small-angle X-ray scattering and electrospray
ionization ion mobility mass spectrometry. We then investigated the
structural transitions of α-Syn to helical structures via association
with large unilamellar vesicles as model lipid membrane systems. Hydrogen–deuterium
exchange combined with electrospray ionization mass spectrometry was
further utilized to understand the details of the regional interaction
mechanisms of α-Syn with lipid vesicles based on the polarity
of the lipid head groups. The characteristics of the helical structures
were observed with α-Syn by adsorption onto the anionic phospholipid
vesicles via electrostatic interactions between the N-terminal region
of the protein and the anionic head groups of the lipids. α-Syn
also associates with zwitterionic lipid vesicles and forms helical
structures via hydrophobic interactions. These experimental observations
provide an improved understanding of the distinct structural change
mechanisms of α-Syn that originate from different regional interactions
of the protein with lipid membranes and subsequently provide implications
regarding diverse protein–membrane interactions related to
their fibrillation kinetics