Proton Inventory and Dynamics in the Ni a -S to Ni a -C Transition of a [NiFe] Hydrogenase

What is it about?

Rapid proton transfer is critical for the proton dependent reactivity of hydrogenases. In this report, a solvent exchangeable proton from an ionizable amino acid hydrogen bonded to the active site is characterized and correlated to the enzymatic chemistry. The ionization state of this undetermined residue is responsible for proton coupled electron transfer to the active site during the hydride formation step of the catalytic cycle.

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Why is it important?

The research described in this paper represents the first experimental attempt to correlate proton inventory to reactivity of a hydrogenase, and observe the effects in real time. This work also significantly advanced the understanding of the [NiFe]-hydrogenases mechanism, defining two new states in the catalytic cycle and describing how they interconvert.