Exploring the Use of a Guanine-Rich Catalytic DNA for Sulfoxide Preparation

Facile immobilization of DNA using an enzymatic his-tag mimic

Methods for immobilization of DNA on solid supports are in high demand. Herein, we present a generally applicable enzymatic method for the immobilization of DNA without any prior chemical derivatization. This strategy relies on the homopolymerization of the modified triphosphate dImTP by the TdT. The resulting enzymatic his-tag mimic ensures binding of DNA on Ni-NTA agarose. The usefulness of this method is highlighted by the immobilization of functional nucleic acids without impairing their specific activities.

Hemin-utilizing G-quadruplex DNAzymes are strongly active in organic co-solvents

The widespread use of organic solvents in industrial processes has focused in recent years on the utility of "green" solvents - those with less harmful environmental, health, and safety properties - such as methanol and formamide. However, protein enzymes, regarded as green catalysts, are often incompatible with organic solvents. Herein, we have explored the oxidative properties of a Fe(III)-heme, or hemin, utilizing catalytic DNA (heme·DNAzyme) in different green solvent-water mixtures. We find that the peroxidase and peroxygenase activities of the heme·DNAzyme are strongly enhanced in 20-30% v/v methanol or formamide, relative to water alone. Protic solvent content of >30% v/v gradually diminishes heme·DNAzyme catalytic activity; however, the heme·DNAzyme is still active in as high as 80% v/v methanol. In contrast to protic solvents, aqueous dimethylformamide solutions largely inhibit heme·DNAzyme activity. In view of the strong catalytic activity of heme·DNAzyme in aqueous methanol, we were able to determine that a 60% v/v methanol-water mixture gives the most optimal yield of the dibenzothiophene sulfoxide (DBTO) oxidation product of petroleum-derived dibenzothiophene (DBT). The high product yield reflects both DNAzyme catalysis and a high substrate availability. Overall, these results emphasize the excellent promise of G-quadruplex forming DNA catalysts in application to "greener" industrial chemistry. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.