ARCHER2 Calendar April 2023

Proton tunnelling during DNA strand separation

Max Winokan, University of Surrey, Quantum Biology DTC

Proton transfer between the DNA bases can lead to mutagenic Guanine-Cytosine tautomers. Over the past several decades, a heated debate has emerged over the biological impact of tautomeric forms. In our work, we determine that the energy required for generating tautomers radically changes during the separation of double-stranded DNA. Our results demonstrate that the unwinding of DNA by a helicase enzyme could significantly enhance the stability of tautomeric base pairs and provide a feasible pathway for DNA spontaneous mutations. This image shows the site of such a double proton transfer in a G-C base pair within the nucleic acid duplex. To produce the image atomic coordinates were taken from molecular dynamics simulations before being rendered in VMD. A Van der Waals envelope was added to show the atoms used in quantum chemical models. The image has been further altered in Photoshop to highlight the delocalised nature of the protons.

This image was published on the April page of the ARCHER2 2023 printed calendar.