Spectral decomposition of iron-sulfur clusters

Betinol, Isaiah; Nader, Serge; Mansy, Sheref S.

doi:10.1016/j.ab.2021.114269

Cited by 9 publications

(16 citation statements)

References 26 publications

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“…FeS cluster species distribution is strongly affected by L-cysteine concentration. As noted by Betinol et al 33 , [4Fe4S] clusters absorb strongly and tend to mask the presence of other clusters on UV-Vis spectroscopy. The concentration-dependence of [4Fe4S] cluster assembly on cysteine concentration and its tight correlation with the signature absorbance shoulder at 420 nm, suggests that other types of cluster were indeed masked by the presence of [4Fe4S] clusters.…”

Section: Resultsmentioning

confidence: 71%

Spontaneous assembly of redox-active iron-sulfur clusters at low concentrations of cysteine

et al. 2021

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Iron-sulfur (FeS) proteins are ancient and fundamental to life, being involved in electron transfer and CO2 fixation. FeS clusters have structures similar to the unit-cell of FeS minerals such as greigite, found in hydrothermal systems linked with the origin of life. However, the prebiotic pathway from mineral surfaces to biological clusters is unknown. Here we show that FeS clusters form spontaneously through interactions of inorganic Fe2+/Fe3+ and S2− with micromolar concentrations of the amino acid cysteine in water at alkaline pH. Bicarbonate ions stabilize the clusters and even promote cluster formation alone at concentrations >10 mM, probably through salting-out effects. We demonstrate robust, concentration-dependent formation of [4Fe4S], [2Fe2S] and mononuclear iron clusters using UV-Vis spectroscopy, 57Fe-Mössbauer spectroscopy and 1H-NMR. Cyclic voltammetry shows that the clusters are redox-active. Our findings reveal that the structures responsible for biological electron transfer and CO2 reduction could have formed spontaneously from monomers at the origin of life.

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Section: Resultsmentioning

confidence: 71%

Spontaneous assembly of redox-active iron-sulfur clusters at low concentrations of cysteine

et al. 2021

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“…Recently, an easy-touse Microsoft Excel based spectral decomposition tool was made freely available. 40 Generally, iron-sulfur clusters absorb in the 300-800 nm range, reflecting the LMCT (ligand-to-metal charge transfer) transitions (Fig. 2A).…”

Section: Uv-vis Absorption Spectroscopymentioning

confidence: 99%

“…42,43 The extinction coefficient of [1Fe-0 S] 3+ rubredoxin at 490 nm is $7000 M -1 cm À1 . 40 Small (≤6 amino acids) [1Fe-0S] 3+ peptides rarely show similar spectra to the rubredoxin protein. Instead, a single broad band at $490 nm is typically observed.…”

Section: Uv-vis Absorption Spectroscopymentioning

confidence: 99%

“…Further, the conditions for the [4Fe-4S] 2+ peptide included 2% (v/v) b-mercaptoethanol. Spectra were plotted from previously published data, 40 and the raw data are available at Zenodo. 50 in the near-UV and visible regions, probing the same electronic transitions seen when collecting absorption spectra as described above.…”

Section: Circular Dichroism Spectroscopymentioning

confidence: 99%

“…Further, the conditions for the [4Fe-4S] 2+ peptide included 2% (v/v) b-mercaptoethanol. Spectra were plotted from previously published data,40 and the raw data are available at Zenodo 50. (B) UV-vis spectrum of 40 mM glutathione, 0.5 mM Na 2 S, and 0.5 mM FeCl 3 at pH 8.6, which contained a mixture of types of iron-sulfur clusters.…”

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confidence: 99%

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Methods to identify and characterize iron–sulfur oligopeptides in water

et al. 2022

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Iron-sulfur clusters are ubiquitous cofactors that mediate central biological processes. However, despite their long history, these metallocofactors remain challenging to investigate when coordinated to small (≤ six amino acids) oligopeptides in aqueous solution. In addition to being often unstable in vitro, iron-sulfur clusters can be found in a wide variety of forms with varied characteristics, which makes it difficult to easily discern what is in solution. This difficulty is compounded by the dynamics of iron-sulfur peptides, which frequently coordinate multiple types of clusters simultaneously. To aid investigations of such complex samples, a summary of data from multiple techniques used to characterize both iron-sulfur proteins and peptides is provided. Although not all spectroscopic techniques are equally insightful, it is possible to use several, readily available methods to gain insight into the complex composition of aqueous solutions of iron-sulfur peptides.

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Prebiotic Environmental Conditions Impact the Type of Iron‐Sulfur Cluster Formed

Valer,

Hu,

Cini

et al. 2024

ChemSystemsChem

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Iron‐sulfur clusters are ancient cofactors that could have played a role in the prebiotic chemistry leading to the emergence of protometabolism. Previous research has shown that certain iron‐sulfur clusters can form from prebiotically plausible components, such as cysteine‐containing oligopeptides. However, it is unclear if these iron‐sulfur clusters could have survived in prebiotically plausible environments. To begin exploring this possibility, we tested the stability of iron‐sulfur clusters coordinated to a tripeptide and to N‐acetyl‐L‐cysteine methyl ester in a variety of solutions meant to mimic prebiotically plausible environments. We also assessed the impact of individual chemical components on stability. We find that iron‐sulfur clusters form over a wide variety of conditions but that the type of iron‐sulfur cluster formed is strongly impacted by the chemical environment and the coordinating scaffold. These findings support the general hypothesis that iron‐sulfur clusters were present on the prebiotic Earth and that different types of iron‐sulfur cluster predominated in different environments.

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Spectral decomposition of iron-sulfur clusters

Cited by 9 publications

References 26 publications

Spontaneous assembly of redox-active iron-sulfur clusters at low concentrations of cysteine

Spontaneous assembly of redox-active iron-sulfur clusters at low concentrations of cysteine

Methods to identify and characterize iron–sulfur oligopeptides in water

Prebiotic Environmental Conditions Impact the Type of Iron‐Sulfur Cluster Formed

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