Oxidative stability of chelated Sn(II) at neutral pH: The critical role of NO ions.

Tin(II) compounds are versatile materials with applications across fields such as catalysis, diagnostic imaging, and therapeutic drugs. However, oxidative stabilization of Sn(II) has remained an unresolved challenge as its reactivity with water and dioxygen results in loss of functionality, limiting technological advancement. Approaches to slow Sn(II) oxidation with chelating ligands or sacrificial electron donors have yielded only moderate improvements.

Evidence of Atypical Structural Flexibility of the Active Site Surrounding of an [FeFe] Hydrogenase from .

[FeFe] hydrogenase from (HydA1) is an unusual hydrogenase in that it can withstand prolonged exposure to O by reversibly converting into an O-protected, inactive state (H). It has been indicated in the past that an atypical conformation of the "SCCP" loop near the [2Fe] portion of the six-iron active site (H-cluster) allows the Cys367 residue to adopt an "off-H-pathway" orientation, promoting a facile transition of the cofactor to H. Here, we investigated the electronic structure of the H-cluster in the oxidized state (H) that directly converts to H under oxidizing conditions and the related CO-inhibited state (H-CO).

Investigation of the Unusual Ability of the [FeFe] Hydrogenase from to Access an O-Protected State.

[FeFe] hydrogenases are enzymes capable of producing and oxidizing H at staggering submillisecond time scales. A major limitation in applying these enzymes for industrial hydrogen production is their irreversible inactivation by oxygen. Recently, an [FeFe] hydrogenase from (HydA1) was reported to regain its catalytic activity after exposure to oxygen.

Analysis of RNA Methylation by Phylogenetically Diverse Cfr Radical -Adenosylmethionine Enzymes Reveals an Iron-Binding Accessory Domain in a Clostridial Enzyme.

Cfr is a radical -adenosylmethionine (SAM) RNA methylase linked to multidrug antibiotic resistance in bacterial pathogens. It catalyzes a chemically challenging C-C bond-forming reaction to methylate C8 of A2503 ( numbering) of 23S rRNA during ribosome assembly. The gene has been identified as a mobile genetic element in diverse bacteria and in the genome of select Bacillales and Clostridiales species.