The Capture of Low-Energy Electrons by PNA versus DNA

This study provides insight into the mechanism of capturing low energy electrons by peptide nucleic acid (PNA) and the role of the oligonucleotide backbone in the capture of low energy electrons. We studied by photoemission self-assembled monolayers of two types of oligonucleotides, DNA and PNA. PNA is a synthetic analogue of DNA that has a pseudopeptide backbone and which may have important medical and biotechological applications. We found that in both PNA and DNA, the guanine nucleobases capture the electrons more efficiently than thymines. In PNA, once the electrons are captured, their state is at least partially localized on the nucleobases, and the PNA molecule undergoes structural changes that stabilize the electron. This situation is in contrast to DNA, in which the captured electrons are transferred very efficiently to the backbone, and the final state of captured electron is base independent.