chemistry

Iron–sulfur cluster

Iron–sulfur cluster is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Iron–sulfur cluster rather than just read about it. In short: Iron–sulfur clusters are molecular ensembles of iron and sulfide. They are most often discussed in the context of the biological role for iron–sulfur proteins, which are pervasive.

Key takeaways

Iron–sulfur cluster belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Iron–sulfur cluster to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Iron–sulfur cluster from memory before moving on to harder problems.

Reference excerpt

Iron–sulfur clusters are molecular ensembles of iron and sulfide. They are most often discussed in the context of the biological role for iron–sulfur proteins, which are pervasive. Many Fe–S clusters are known in the area of organometallic chemistry and as precursors to synthetic analogues of the biological clusters. It is supposed that the last universal common ancestor had many iron-sulfur clusters.

In biology

Iron–sulfur clusters occur in many biological systems, often as components of electron transfer proteins. The ferredoxin proteins are the most common Fe–S proteins in nature. They feature either 2Fe–2S or 4Fe–4S centers. They occur in all branches of life. Fe–S clusters can be classified according to their Fe:S stoichiometry [2Fe–2S], [4Fe–3S], [3Fe–4S], and [4Fe–4S]. The [4Fe–4S] clusters occur in two forms: normal ferredoxins and high potential iron proteins (HiPIP). Both adopt cuboidal structures, but they utilize different oxidation states. They are found in all forms of life. The relevant redox couple in all Fe–S proteins is Fe(II)/Fe(III). Many clusters have been synthesized in the laboratory with the formula [Fe4S4(SR)4]2−, which are known for many R substituents, and with many cations. Variations have been prepared including the incomplete cubanes [Fe3S4(SR)3]3−.

Synthetic Fe–S clusters

Synthetic Fe–S clusters are laboratory-prepared coordination compounds or chains, often designed to mimic the structural, electronic, or chemical properties of biological Fe–S clusters. Roussin's black anion, [Fe4S3(NO)7]−, described in 1858, is the first synthetic Fe-S cluster. It has the geometry of an incomplete cubane-type cluster with C3v symmetry. The dark color of the complex is attributed to a number of charge-transfer interactions. Since the 1970s, many of these Fe-S clusters have been described. A key property of Fe–S clusters is their ability to undergo redox.

Organometallic clusters Organometallic Fe–S clusters include the sulfido carbonyls with the formula Fe2S2(CO)6, H2Fe3S(CO)9, and Fe3S2(CO)9. Compounds are also known that incorporate cyclopentadienyl ligands, such as (C5H5)4Fe4S4.

Inorganic materials

In maquettes and artificial proteins It is possible to incorporate Fe–S clusters into maquettes (smaller minimal functional proteins designed from biological proteins) and artificial proteins, often abbreviated to MAPs. The first examples of Fe–S MAPs emerged in the early 1970s, as a means to mimic naturally occurring iron-containing proteins like rubredoxins. These contained [Fe(S-Cys)4] motifs. Further research into [4Fe–4S] MAPs has led to the development of ambidoxins: de novo maquettes that consist of 12 residues with the sequence X-Cys-X2-Cys-X2-Cys-X2-Cys-X (X = Arg, Lys), which can successfully perform hundreds of redox cycles. However, Fe–S MAPs are limited by their lower solubility and exposed Fe–S cluster core that is susceptible to degradation by solvents.

See also Bioinorganic chemistry Ligand (biochemistry) Iron-binding proteins Biometal (biology) FeMoco

References

External links

Illustrations

Worked examples

Example 1 — a first encounter with Iron–sulfur cluster

Start with the simplest possible case. Write down what Iron–sulfur cluster claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Iron–sulfur cluster before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Iron–sulfur cluster ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Iron–sulfur cluster

In research: Iron–sulfur cluster appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Iron–sulfur cluster in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Iron–sulfur cluster is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cluster chemistry, Cubane-type clusters, Iron compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Iron–sulfur cluster outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Iron–sulfur cluster in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Iron–sulfur cluster means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Iron–sulfur cluster out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Iron–sulfur cluster in simple terms?

Iron–sulfur clusters are molecular ensembles of iron and sulfide. They are most often discussed in the context of the biological role for iron–sulfur proteins, which are pervasive.

Why does Iron–sulfur cluster matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Iron–sulfur cluster?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Iron–sulfur cluster.