Glutamate Gated Proton-Coupled Electron Transfer Activity of a [NiFe]-Hydrogenase

What is it about?

Enzymes which are capable of reducing protons to form hydrogen (Hydrogenases) display a remarkable ability to move protons and electrons rapidly and in a coupled fashion to achieve catalysis, rivaling synthetic catalysts. The mechanism of electron transport is well understood, but proton transport has been much more challenging to assess. In this paper, mutations at a putative proton transport channel are introduced and the effects on proton and electron transfer are observed. It is found that a glutamate near the active site and conserved in all [NiFe] Hydrogenases facilitates this process.

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Why is it important?

The demonstration of a glutamate which controls a coupled proton and electron transfer event is important, as this establishes the first step in a "structure/function" relationship between the enzyme's architecture and its reactivity. From this structure/function understanding, new Hydrogenases could be engineered with unique reactivity, or this design principle could be integrated into an artificial biomimetic catalyst to emulate the native system's phenomenal efficiency.