Final Report Summary - ET DPHEN DNA (Electron transfer through multiple consecutive phenanthrenyl containing DNA)
This project had three interconnected goals aimed at improving our understanding of reductive electron transfer in DNA. Our first goal was to synthesise DNA containing aromatic nucleobase surrogates that can facilitate electron transfer in a DNA double helix. Next, we pursued the synthesis of electron donors with a higher reduction potential when compared to the aromatic nucleobase surrogates. Our last goal was to discover and design novel electron acceptors that can report on electron transfer by a fluorescent response.
We have made progress in all three of the above research goals. We accomplished the synthesis of various pyrene and phenanthrene aromatic nucleobase surrogates that vary in their electron affinity. With respect to the electron donors we have synthesised phenothiazine and 1,5-diaminonapthalene electron donors that are compatible with oligonucleotide synthesis. Lastly, we designed and synthesised new electron acceptors that may report on electron transfer by a fluorescent response. The first generation electron acceptor was based on a well know highly fluorescent cytosine analogue. However, the substituted cytosine nucleobase did not produce any desired fluorescence quenching so we redesigned our approach for the discovery of these electron acceptors. Instead of substituting known fluorescent nucleobases with a fluorescence quencher and testing for fluorescence quenching we decided to conjugate fluorescent molecules that have previously shown to undergo quenching to the natural nucleobases. We attached a fluorescently quenched anthracene to deoxyuridine and indeed the quenching was preserved. In the future, the phenothiazine (PTZ) and 1,5-diaminonapthalene electron donors will be incorporated into DNA and tested for their ability to report on electron transfer by a fluorescent response.
The above mentioned work will not only broaden our understanding of electron transfer through DNA but the combination of electron transfer with a fluorescence response may lead to new bioanalytical methods for detecting base mismatch and DNA damage.
We have made progress in all three of the above research goals. We accomplished the synthesis of various pyrene and phenanthrene aromatic nucleobase surrogates that vary in their electron affinity. With respect to the electron donors we have synthesised phenothiazine and 1,5-diaminonapthalene electron donors that are compatible with oligonucleotide synthesis. Lastly, we designed and synthesised new electron acceptors that may report on electron transfer by a fluorescent response. The first generation electron acceptor was based on a well know highly fluorescent cytosine analogue. However, the substituted cytosine nucleobase did not produce any desired fluorescence quenching so we redesigned our approach for the discovery of these electron acceptors. Instead of substituting known fluorescent nucleobases with a fluorescence quencher and testing for fluorescence quenching we decided to conjugate fluorescent molecules that have previously shown to undergo quenching to the natural nucleobases. We attached a fluorescently quenched anthracene to deoxyuridine and indeed the quenching was preserved. In the future, the phenothiazine (PTZ) and 1,5-diaminonapthalene electron donors will be incorporated into DNA and tested for their ability to report on electron transfer by a fluorescent response.
The above mentioned work will not only broaden our understanding of electron transfer through DNA but the combination of electron transfer with a fluorescence response may lead to new bioanalytical methods for detecting base mismatch and DNA damage.