Reactivation of sulfide-protected [FeFe] hydrogenase in a redox-active hydrogel

Abstract

[FeFe] hydrogenases are highly active hydrogen conversion catalysts, whose oxygen sensitivity prevents their widespread application. Here, an oxygen-stable inactive form was reactivated in a redox hydrogel enabling its practical use under air.

Photochemistry and photoinhibition of the H-cluster of FeFe hydrogenases

“…In the H ox -CO and H inact states, extrinsic CO or HSligands, respectively, coordinate the Fe D apical site 67,68 (Figure 1). Both CO and sulfide binding prevent the damage of the enzyme by O 2 [69][70][71] , showing that they target the same binding site as O 2 68,72…”

Bioelectrocatalytic Cofactor Regeneration Coupled to CO2 Fixation in a Redox‐Active Hydrogel for Stereoselective C−C Bond Formation

“…Although redox‐active hydrogels were previously used for the regeneration of NADH[ 9 , 10 ] their application has not yet been demonstrated for the recycling of NADPH. We use a recently reported 2,2′‐viologen modified polyvinyl alcohol (V 2+ ‐PVA)[ 13 , 14 ] as low‐potential redox polymer for the immobilization of FNR from Synechococcus sp. directing electrons towards the reduction of NADP + .…”

“…Bioelectrocatalytic NADP + Reduction Although redox-active hydrogels were previously used for the regeneration of NADH [9,10] their application has not yet been demonstrated for the recycling of NADPH. We use ar ecently reported 2,2'-viologen modified polyvinyl alcohol (V 2+ -PVA) [13,14] as low-potential redox polymer for the immobilization of FNR from Synechococcus sp.d irecting electrons towards the reduction of NADP + .T he biocatalytic film (Figure 1A), formed by drop casting am ixture of V 2+ -PVAa nd FNR onto ag lassy carbon electrode,w as first characterized with cyclic voltammetry (CV). Ther edox potential of V 2+ -PVAw as determined at À466 mV vs.S HE being 110 mV more negative than the standard redox potential of the NADP + /NADPH pair (À355 mV at pH 8 [15] ) thus providing sufficient driving force for the electron transfer to FNR (Figure 1B).…”

Artificial maturation of [FeFe] hydrogenase in a redox polymer film

“…[13][14][15] It is also possible to prepare polymer films of [FeFe] hydrogenase under aerobic conditions by protecting the anaerobically purified hydrogenase using a sulfide inhibitor, 11 and then reactivating it by removing the sulfide under anaerobic conditions. 16 Here we show that we can embed the apo-enzyme in a film of redox polymer and mature it by exposing the film to the dinuclear complex. The activation is fast, suggesting that the polymer does not hamper the diffusion of the complex, nor its incorporation into the apo-enzyme.…”