ja5b08769_si_001.pdf (1.45 MB)
A Molecular Chaperone for G4-Quartet Hydrogels
journal contribution
posted on 2016-01-13, 00:00 authored by Gretchen
Marie Peters, Luke P. Skala, Jeffery T. DavisThioflavin
T (ThT) functions as a molecular chaperone for gelation
of water by guanosine and lithium borate. Substoichiometric ThT (1
mol % relative to hydrogelator) results in faster hydrogelation as
monitored by 1H NMR and visual comparison. Vial-inversion
tests and rheology show that ThT increases the stiffness of the Li+ guanosine-borate (GB) hydrogel. In addition, the dye promotes
relatively rapid and complete repair of a Li+ GB hydrogel
destroyed by shearing. We used rheology to show that other planar
aromatics, some cationic and one neutral dye (methylene violet), also
stiffened the Li+ GB hydrogel. Data from powder X-ray diffraction,
UV, and circular dichroism spectroscopy and ThT fluorescence indicate
that G4 quartets are formed by the Li+ GB system. We observed
a species in solution by 1H NMR that was intermediate in
size between monomeric gelator and NMR-invisible hydrogel. The concentration
of this intermediate decreased much faster when ThT was present in
solution, again showing that the dye can accelerate hydrogel formation.
We propose that ThT functions as a molecular chaperone by end stacking
on terminal G4-quartets and promoting the assembly of these smaller
fragments into longer G4-based structures that can then provide more
cross-linking sites needed for hydrogelation.