O2 Reactions at the Six-iron Active Site (H-cluster) in [FeFe]-Hydrogenase*

O2 reduction and O2-induced damage at the active site of FeFe hydrogenase

FeFe hydrogenases are the most efficient H2 producing enzymes, but inactivation by O2 is an obstacle to using them in biotechnological devices. Here we combine electrochemistry, sitedirected mutagenesis, molecular dynamics and quantum chemical calculations to uncover the molecular mechanism of O2 diffusion within the enzyme and its reactions at the active site. We find that the partial reversib...

Synthetic [FeFe] Hydrogenase Active Site Model Complexes

Coordination and conformational isomers in mononuclear iron complexes with pertinence to the [FeFe] hydrogenase active site.

A series of six mononuclear iron complexes of the type [Fe(X-bdt)(P(R)2N(Ph)2)(CO)] (P(R)2N(Ph)2 = 1,5-diaza-3,7-diphosphaoctane, bdt = benzenedithiolate with X = H, Cl2 or Me and R = Ph, Bn, Cyc or tert-Bu) was prepared. This new class of penta-coordinate iron complexes contains a free coordination site and a pendant base as essential structural features of the [FeFe]-hydrogenase active site. ...

Lyophilization protects [FeFe]-hydrogenases against O2-induced H-cluster degradation

Nature has developed an impressive repertoire of metal-based enzymes that perform complex chemical reactions under moderate conditions. Catalysts that produce molecular hydrogen (H2) are particularly promising for renewable energy applications. Unfortunately, natural and chemical H2-catalysts are often irreversibly degraded by molecular oxygen (O2). Here we present a straightforward procedure b...

[FeFe]-Hydrogenase with Chalcogenide Substitutions at the H-Cluster Maintains Full H2 Evolution Activity.

The [FeFe]-hydrogenase HYDA1 from Chlamydomonas reinhardtii is particularly amenable to biochemical and biophysical characterization because the H-cluster in the active site is the only inorganic cofactor present. Herein, we present the complete chemical incorporation of the H-cluster into the HYDA1-apoprotein scaffold and, furthermore, the successful replacement of sulfur in the native [4FeH ]...