Here we will discuss recent results from our work in which we show conditionally active electron transfer catalysts can be constructed from DNA. The catalysts are comprised of two strands, one of which can be selectively switched between a G-quadruplex and duplex or single-stranded conformations. This switching ability arises from our recent discovery that perchlorate, a chaotropic Hofmeister ion, selectively destabilizes duplex over G-quadruplex DNA. By varying perchlorate concentration, we show that the device can be operated as a switch or signal amplifier. State switching can be achieved in three ways: thermally, by dilution, or by concentration. In each case, when operated in the presence of the cofactor hemin, the device catalyzes electron transfer in only the G-quadruplex state. Examples of secondary-structure remodeling are observed in life as well. Nucleic acids exhibit considerable polymorphism in biological systems, particularly in sequences that can form G-Quadruplexes. Several proteins can remodel G-quadruplexes, and both energy-dependent (i.e., helicases) and energy-independent systems that can do so have been reported. ATPdependent helicases are known to unwind G-quadruplex structures, and the RNA-binding protein Lin28 has been shown to unfold G-quadruplexes without the requirement for ATP. The structure switching performed by Hofmeister ions in this work thus amounts to a bioinspired means of performing such remodeling, which in turn enables a functional behavior (electron transfer).

Conditionally active electron transfer catalysts enabled by bioinspired remodeling of polymer secondary structure

ACS Fall 2021

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