# Proton tunneling in hydrogen bonds and its implications in an induced-fit model of enzyme catalysis

## TL;DR

This paper explores how proton tunneling and quantum correlations in hydrogen bonds contribute to enzyme catalysis, suggesting that quantum effects can significantly lower activation energy and facilitate reactions.

## Contribution

It introduces a quantum information and thermodynamics framework to explain enzyme catalysis via proton tunneling and quantum correlations in hydrogen bonds.

## Key findings

- Quantum correlations are generated between hydrogen-bonded atoms during enzyme binding.
- Enzymes can induce quantum superpositions that drive tautomerization without energy barriers.
- Quantum effects can lower activation energy even when correlations decay rapidly.

## Abstract

The role of proton tunneling in biological catalysis is investigated here within the frameworks of quantum information theory and thermodynamics. We consider the quantum correlations generated through two hydrogen bonds between a substrate and a prototypical enzyme that first catalyzes the tautomerization of the substrate to move on to a subsequent catalysis, and discuss how the enzyme can derive its catalytic potency from these correlations. In particular, we show that classical changes induced in the binding site of the enzyme spreads the quantum correlations among all of the four hydrogen-bonded atoms thanks to the directionality of hydrogen bonds. If the enzyme rapidly returns to its initial state after the binding stage, the substrate ends in a new transition state corresponding to a quantum superposition. Open quantum system dynamics can then naturally drive the reaction in the forward direction from the major tautomeric form to the minor tautomeric form without needing any additional catalytic activity. We find that in this scenario the enzyme lowers the activation energy so much that there is no energy barrier left in the tautomerization, even if the quantum correlations quickly decay.