A Redox Hydrogel Protects the O₂‐Sensitive [FeFe]‐Hydrogenase from Chlamydomonas reinhardtii from Oxidative Damage

Abstract

The integration of sensitive catalysts in redox matrices opens up the possibility for their protection from deactivating molecules such as O2 . [FeFe]-hydrogenases are enzymes catalyzing H2 oxidation/production which are irreversibly deactivated by O2 . Therefore, their use under aerobic conditions has never been achieved. Integration of such hydrogenases in viologen-modified hydrogel films allows the enzyme to maintain catalytic current for H2 oxidation in the presence of O2 , demonstrating a protection mechanism independent of reactivation processes. Within the hydrogel, electrons from the hydrogenase-catalyzed H2 oxidation are shuttled to the hydrogel-solution interface for O2 reduction. Hence, the harmful O2 molecules do not reach the hydrogenase. We illustrate the potential applications of this protection concept with a biofuel cell under H2 /O2 mixed feed.

Artificial Maturation of the Highly Active Heterodimeric [FeFe] Hydrogenase from Desulfovibrio desulfuricans ATCC 7757

“…However, since Dd HydAB is at least an order of magnitude more active than Cr HydA1, a comparison between the effects of different H‐clusters in the two species may provide useful insight into the relative importance of different properties of the H‐cluster. Recently, the [NiFe] and [FeFe] hydrogenases were shown to be protected from oxygen damage by embedding them in redox hydrogels . Dd HydAB may also be protected using this method and this may then provide an even more active system applicable to devices for hydrogen production or hydrogen usage.…”

Electrochemical Investigations on the Inactivation of the [FeFe] Hydrogenase from Desulfovibrio desulfuricans by O2 or Light under Hydrogen‐Producing Conditions

“…This has also prevented successful implementation of photobiological H 2 production using green algae or cyanobacteria . Only recently, a redox polymer was used to protect the [FeFe] hydrogenase Cr HydA1 from oxidative damage and its applicability in a fuel cell was demonstrated . Direct wiring of Clostridium acetobutylicum hydrogenase ( Ca HydA1) to photosystem I led to efficient H 2 production using light and a sacrificial electron donor under anaerobic conditions …”

Microalgal hydrogen production research

“…Based on 100 m 3 volume of a microalgal culture, their system yielded an average power of about 72 W for 50 h under a 10 U load at a stable voltage of 110 mV [197], which compared favorably with the theoretical maximum of 240 W for 100 h of a PEM fuel cell operated on the basis of the same volume of a C. reinhardtii culture [198]. Oughli et al [199] used a viologen-modified hydrogel for the protection of the C. reinhardtii [FeFe]-hydrogenase from O 2 by quenching it before reaching the hydrogenase. This approach was successfully utilized in a single-compartment fuel cell with an inlet of a H 2 and O 2 gas mixture.…”