Click Chemistry Assisted
Single-Molecule Fingerprinting
Reveals a 3D Biomolecular Folding Funnel
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Abstract
A 3D folding funnel was proposed in the 1990s to explain
the fast
kinetics exhibited by a biomacromolecule in presence of seemingly
unlimited folding pathways. Over the years, numerous simulations have
been performed with this concept; however, experimental verification
is yet to be attained even for the simplest proteins. Here, we have
used a click chemistry based strategy to introduce six pairs of handles
in a human telomeric DNA sequence. A laser-tweezers-based, single-molecule
structural fingerprinting on the six inter-handle distances reveals
the formation of a hybrid-1 G-quadruplex in the sequence. Kinetic
and thermodynamic fingerprinting on the six trajectories defined by
each handle-pair depict a 3D folding funnel and a kinetic topology
in which the kinetics pertaining to each handle residue is annotated
for this G-quadruplex. We anticipate the methods and the concepts
developed here are well applicable to other biomacromolecules, including
RNA and proteins