A unique sixth-order reversible assembly of hexameric mimetic nucleic acid

Alpha DPNA strands bearing melamine and cyanuric acid assemble in water into a cylindrical hexameric structure with a highly cooperative, enthalpically driven equilibrium (molecularity 6.2 ± 0.2).

• Why it matters: Simple macroscopic kinetics can hide complex microscopic steps, and the field lacks clear examples linking two-state spectroscopic behavior to underlying multi-step assembly mechanisms.
• What they did: The authors mixed equimolar complementary alpha DPNA and used circular dichroism with singular-value decomposition to test for intermediates, then fit equilibrium and progress curves to a reversible sixth-order macroscopic rate law.
• The result: The assembly shows an association constant of (2.3 ± 0.2)×10^22 M^(-5) and a negative activation energy for the apparent forward rate, which a pre-isomerization model (and constrained sequential simulations) explains while preserving the two-state CD signature.

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