The results described above illustrate the exciting potential of PNA.
In this case, it provides a tool for probing long range electron
transfer through stacked π-electron systems as well as for the
photomodification of complementary DNA strands. The ability to cleave
DNA in PNA/DNA hybrids by the same mechanisms that operate in DNA/DNA
duplexes is a further demonstration of the remarkable ability of PNA to
mimic DNA. Although there are reports of the use of PNA–nuclease
conjugates for the site-specific cleavage of double-stranded DNA (26
), these experiments provide the first example in which PNA cleaves single-stranded DNA targets. Extension of these studies
to electron transport within PNA/PNA duplexes and PNA2
triplexes is planned as are experiments that will assess the ability of
the PNA strand to trap oxidative damage. The ease of synthesizing
internally modified PNA, the stability of the resulting hybrid
duplexes, and their ability to mimic the reactivity of duplex DNA
should contribute to the growing application of PNA in chemistry,
biochemistry, and medicine.