Metal Ion-Induced
Unusual Stability of the Metastable
Vesicle-like Intermediates Evolving during the Self-Assembly of Phenylalanine:
Prominent Role of Surface Charge Inversion
posted on 2024-04-17, 20:45authored byDebanjan Bagchi, Avijit Maity, Anjan Chakraborty
The underlying mechanism and intermediate
formation in
the self-assembly
of aromatic amino acids, peptides, and proteins remain elusive despite
numerous reports. We, for the first time, report that one can stabilize
the intermediates by tuning the metal ion–amino acid interaction.
Microscopic and spectroscopic investigations of the self-assembly
of carboxybenzyl (Z)-protected phenylalanine (ZF) reveal that the
bivalent metal ions eventually lead to the formation of fibrillar
networks similar to blank ZF whereas the trivalent ions develop vesicle-like
intermediates that do not undergo fibrillation for a prolonged time.
The time-lapse measurement of surface charge reveals that the surface
charge of blank ZF and in the presence of bivalent metal ions changes
from a negative value to zero, implying unstable intermediates leading
to the fibril network. Strikingly, a prominent charge inversion from
an initial negative value to a positive value in the presence of trivalent
metal ions imparts unusual stability to the metastable intermediates.