Structural and catalytic properties of DNA/RNA-heme complexes

DNA and RNA G-quadruplexes have been shown to catalyze 1-electron oxidation reactions when bound to heme. In this work, we set out to explore the fundamental nature of G-quadruplexes that allow for heme binding, and the potential of nucleoheme complexes in catalyzing other heme-related enzymatic reactions. A combination of spectroscopic and gel-based tools was used to observe structural features of nucleoheme complexes. We determined that the in vitro selected heme apatamer, PS2.M, is highly polymorphic and predominantly parallel-stranded. The ability of many parallel G-quadruplexes to bind heme and perform peroxidase reactions led us to believe that some nucleoheme complexes may be capable of catalyzing oxygen transfer or 2-electron oxidation reactions. By using gas chromatography and high performance liquid chromatography analysis, we determined that nucleoheme complexes were capable of oxidizing electron-rich substrates: thioanisole, indole, and styrene. This discovery has expanded the catalytic repertoire of nucleic acids, which leads to questions about the consequences and potential of this catalytic ability.