Biological and Medicinal Chemistry

Spectroscopic investigations under whole cell conditions provide new insight into the metal hydride chemistry of [FeFe]-hydrogenase

Abstract

Hydrogenases are among the fastest H2 evolving catalysts known to date and have been extensively studied under in vitro conditions. Here, we report the first mechanistic investigation of an [FeFe]-hydrogenase under in vivo conditions. Functional [FeFe]-hydrogenase from the green alga Chlamydomonas reinhardtii is generated in genetically modified Escherichia coli cells, by addition of a synthetic cofactor to the growth medium. The assembly and reactivity of the resulting semi-synthetic enzyme was monitored using whole-cell electron paramagnetic resonance as well as Fourier-transform infrared spectroscopy. Through a combination of gas treatments, pH titrations and isotope editing, we were able to corroborate the physiological relevance of a number of proposed catalytic intermediates, including reactive iron-hydride species. We demonstrate the formation of the so-called hydride state in vivo. Moreover, two previously uncharacterized redox species are reported herein, illustrating the complex metal hydride chemistry of [FeFe]-hydrogenase.

Content

Thumbnail image of In vivo spectroscopy MS Berggren.pdf

Supplementary material

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TOC
Thumbnail image of In vivo spectroscopy SI GBerggren.pdf
In vivo spectroscopy SI GBerggren