EisenSulfurClustern

EisenSulfurClustern, known in English as iron-sulfur clusters, are inorganic cofactors composed of iron and sulfur atoms arranged into discrete poly-nuclear assemblies. In biological systems they are typically bound to proteins through cysteine thiolate ligands, while synthetic models use various stabilizing ligands. The clusters span from two-iron to four-iron cores, with common structures such as [Fe2S2], [Fe3S4], and [Fe4S4]. Their redox-active nature enables rapid electron transfer and catalytic versatility.

Structural motifs of EisenSulfurClustern fall into a few well-established geometries. The most prominent are cubane-type [Fe4S4] clusters, in which four iron and four sulfur atoms form a compact cube, and non-cubane assemblies like [Fe2S2] and [Fe3S4]. Ligation patterns primarily involve cysteine thiolates, but histidine or inorganic ligands can also coordinate iron. The clusters can cycle through multiple oxidation states, commonly involving Fe(II)/Fe(III) couples, which underpins their electron-transfer functions.

Biological roles are diverse. EisenSulfurClustern serve as electron carriers in ferredoxins and high-potential iron-sulfur proteins, participate in catalytic processes in nitrogenase and hydrogenase, and act as cofactors in radical SAM enzymes that generate radical species for complex transformations. They also participate in respiration and photosynthesis as components of electron-transport chains and metabolic catalysts. Their redox flexibility makes them central to cellular energy flow and substrate activation.

Biosynthesis and maturation of EisenSulfurClustern are tightly regulated. In bacteria and archaea, dedicated ISC and SUF systems assemble clusters on scaffold proteins (e.g., IscU) before insertion into apoproteins, with chaperones facilitating transfer. Oxidative stress can disrupt clusters, necessitating repair or replacement pathways.

Applications and research focus on EisenSulfurClustern include mechanistic studies of electron transfer, development of bioinspired catalysts, and modeling of complex natural systems. They remain a cornerstone of bioinorganic chemistry and materials science due to their rich redox chemistry and structural tunability. See also iron–sulfur proteins, radical SAM enzymes, and cluster biosynthesis.