Linking experiment to theory: Quantum entanglement during enzyme catalysis

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Physicists generally describe the world around them using one of two different models: classical Newtonian mechanics and quantum mechanics. While Newton developed his theory to describe the motion of the planets, quantum mechanics, due to it's greater complexity, is typically only used to describe systems of a few atoms or less. Despite this, quantum mechanics remains an exciting area of research, with its application leading to recent breakthroughs in teleportation and information theory. Biologists have often ignored quantum mechanics, yet it is now becoming evident that quantum mechanical tunnelling plays a significant role during simple biological electron and hydrogen transfer reactions. During these reactions, the wave/particle duality of the transferred electron or hydrogen allows its position to become delocalised (smeared out over space), thus affecting the way the reaction proceeds. An even stranger consequence of quantum mechanics is superposition and entanglement, where the quantum states of two or more distant objects are linked. The proposed research aims to utilise methods we have developed while investigating electron and hydrogen tunnelling reactions to determine whether other quantum mechanical phenomena influence biology processes. Specifically, this research aims to look for evidence of entanglement of different substrate molecules in the active sites of enzymes such as DNA polymerase - an idea that has recently emerged from studies of quantum search algorithms. DNA - 'the molecule of life' - is a polymer of four different nucleotide monomers (dNTPs), denoted A, T, C and G. DNA replication, the method by which living organisms copy their DNA prior to cell division, is the basis for biological inheritance. During replication, each strand of the double-stranded DNA helix can act as a template for the reproduction of another strand of DNA. This replication is catalysed by DNA polymerase, an enzyme that once bound to a section of single stranded DNA template, produces double-stranded DNA by moving along the template strand adding the required dNTP, one at a time. As only one dNTP substrate can bind at a time, it should take four attempts for DNA polymerase to find the correct dNTP (A, T, C or G) during each step of replication. However, in a quantum mechanical world, it is theoretically possible that two or more dNTPs could become entangled and simultaneously superimposed within the active site of DNA polymerase. If this is the case, the enzyme could pre-select the correct substrate without having to perform a blind search for the correct dNTP. This research aims to use a combination of experimental enzymology and computational/theoretical chemistry to determine whether such an entanglement of substrates is possible. This approach can then be extended to investigate many other biologically important enzymes that act on multiple substrates. Further, as mutations are caused by errors in DNA replication due to occasional DNA polymerase infidelity, a greater understanding of how this enzyme distinguishes between its four dNTP substrates could lead to preventative treatments of aging and cancer. Additionally, if quantum entanglement plays an observable role during catalysis, this would demonstrate that coherent quantum states can have 'useful' lifetimes - an important question in theoretical physics and particularly in the emerging field of quantum computing.