Dr. Gino DiLabio:
Head of Chemistry, UBC-Okanagan
Radical enzymes are a large class of enzymes that make use of highly reactive radicals to affect thermodynamically challenging chemistry. These proteins generate primary carbon-centred radicals in their active sites which initiate difficult chemistry by abstracting a hydrogen atom from a substrate molecule.
But how does the enzyme prevent the radical from abstracting a hydrogen atom from the protein itself and damaging it irreparably?
Our preliminary quantum mechanical simulation work has revealed that radical enzyme active sites may have evolved to control the reactivity of radicals using the little known and poorly understood quantum Coulombic effect (QCE).
When away from the substrate, the QCE alters the electronic configuration of the radical to a non-Aufbau arrangement, rendering it far less reactive.
When the radical is close to the substrate, the QCE is “turned off” restoring the reactivity of the radical. In this presentation, I will discuss the QCE and our findings to date on the role of the QCE in radical enzymes.