Characterization of [FeFe] Hydrogenase O2 Sensitivity Using a New, Physiological Approach
[FeFe] hydrogenases catalyze rapid H2 production but are highly O2 sensitive. Developing O2-tolerant enzymes is needed for sustainable H2 production technologies, but the lack of a quantitative and predictive assay for O2 tolerance has impeded progress. We determine a new approach to provide quantitative assessment of O2 sensitivity by using an assay employing ferredoxin NADP+ reductase (FNR) to transfer electrons from NADPH to hydrogenase via ferredoxins (Fd). Hydrogenase inactivation is measured during H2 production in an O2-containing environment. An alternative assay uses dithionite (DTH) to provide reduced Fd. This second assay measures the remaining hydrogenase activity in periodic samples taken from the NADPH-driven reaction sequence. The second assay validates the more convenient NADPH-driven assay which better mimics physiological conditions. During development of the NADPH-driven assay and while characterizing the Clostridium pasteurianum (Cp) [FeFe] hydrogenase, CpI, we detected significant rates of direct electron loss from reduced Fd to O2. Yet, this loss does not interfere with measurement of first order hydrogenase inactivation, providing rate constants insensitive to initial hydrogenase concentration. We show increased activity and O2 tolerance for a protein fusion between Cp ferredoxin (CpFd) and CpI mediated by a 15 amino acid linker but not for a longer linker. Here, we suggest that this precise, solution phase assay for [FeFe] hydrogenase O2 sensitivity and the insights we provide constitute an important advance toward the discovery of the O2 tolerant [FeFe] hydrogenases required for photosynthetic, biological H2 production.
- Research Organization:
- Stanford Univ., CA (United States)
- Sponsoring Organization:
- USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; National Science Foundation (NSF)
- Grant/Contract Number:
- FG02–09ER46632; SC0002010
- OSTI ID:
- 1769189
- Alternate ID(s):
- OSTI ID: 1535356
- Journal Information:
- Journal of Biological Chemistry, Journal Name: Journal of Biological Chemistry Vol. 291 Journal Issue: 41; ISSN 0021-9258
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
O 2 sensitivity and H 2 production activity of hydrogenases—A review
|
journal | August 2019 |
Clostridial whole cell and enzyme systems for hydrogen production: current state and perspectives
|
journal | November 2018 |
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