Understanding proton movement in [FeFe]-hydrogenase
EMSL Project ID
60269
Abstract
This proposed work ultimately aims to elucidate enzymatic design principles for proton transfer. We will employ the smallest and most NMR “friendly” version of this highly studied and well-known paramagnetic metalloenzymatic system, [FeFe]-hydrogenase (H2ase). Chlamydomonas reinhardtii (Cr) produces a 49 kDa H2ase containing only one accessory FeS cluster as an electron wire. This is extremely advantageous as the paramagnetic sphere inherent to H2ase is smaller, thus allowing observation of an increased number of amide cross peaks. Proton movement is ubiquitous and fundamental to biological systems. Furthermore, efficiently shuttling protons has been shown to be incredibly important for creating molecular biomimetic electrocatalysts competent for both hydrogen oxidation and hydrogen production reactions. Unfortunately, there is a disparity of published work directly applied to investigating proton movement in electrocatalytic enzymatic systems. Most likely due to the difficulty inherent to this task. For this venture, we will employ a thoroughly understood electrocatalytic enzymatic system, HydA1 an H2ase from Cr. The H2ase machinery spectacularly interconverts H2 gas to protons and electrons (H2 oxidation) and the reverse reaction (H2 production) with incredibly low energy input and amazingly fast kinetics. Although there is a great deal of structural homology between H2ase systems, the preference for catalytic activity for a given system has been finely tuned by evolutionary pressure, thus creating a catalytic preference for H2ase’s from various organisms where H2 oxidation or H2 production may be more essential to ensure environmental fitness. Clearly, H2ase has been extensively studied and a plethora of electrocatalytic data can be found in the literature, however, we still cannot interconvert one H2ase with a catalytic preference for hydrogen production to a system with a preference for hydrogen oxidation. We aim to design mutant protein scaffolds of H2ase to destroy the native proton pathway, thereby elucidating important design principles for proton movement, with the goal of transferring these design principles to systems for CO2 related chemistry. The scientific premise is that proton transport in biological systems has evolved to expertly regulate proton delivery and removal, and these principles are transferable between systems. A wealth of previously compiled electrocatalytic data is crucial for expedited understanding of the data obtained herein, and thus building from a well-known system is a strength for this proposed work. We will evaluate and compare both proton and electron movements using nuclear magnetic resonance and electrochemical techniques, respectively, by creating a series of mutants that destroy the native proton delivery/removal chains and install new pathways using computational advice thus allowing us to couple proton movement with catalytic activity.
Project Details
Start Date
2021-12-28
End Date
2022-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members