# Sub-picosecond proton tunnelling in deformed DNA hydrogen bonds under an asymmetric double-oscillator model

## TL;DR

This paper models proton tunnelling in DNA hydrogen bonds using a double oscillator framework, revealing that under certain deformations, tunnelling occurs in sub-picosecond timescales relevant to biological processes.

## Contribution

It introduces a novel asymmetric double oscillator model for proton tunnelling in DNA, showing how geometric deformations significantly reduce tunnelling times to biologically relevant scales.

## Key findings

- Proton tunnelling times can be reduced by up to 40 orders of magnitude with asymmetry.
- Tunnelling occurs in less than one picosecond under most planar deformations.
- The model links proton tunnelling to biological phenomena like mutations.

## Abstract

We present a model of proton tunnelling across DNA hydrogen bonds, compute the characteristic tunnelling time (CTT) from donor to acceptor and discuss its biological implications. The model is a double oscillator characterised by three geometry parameters describing planar deformations of the H bond, and a symmetry parameter representing the energy ratio between ground states in the individual oscillators. If the symmetry parameter takes its maximum value of 1, then we recover a known model which produced CTTs too large to be biologically relevant; but this is reduced by up to 40 orders of magnitude as the symmetry parameter is decreased. We discover that unless the symmetry parameter is close to 1 or 0, the proton's CTT under any planar deformation is guaranteed to be below one picosecond, which is a biologically relevant time-scale. This supports theories of links between proton tunnelling and biological processes such as spontaneous mutation.