biology

Methylated-DNA—(protein)-cysteine S-methyltransferase

Methylated-DNA—(protein)-cysteine S-methyltransferase is a biology 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 Methylated-DNA—(protein)-cysteine S-methyltransferase rather than just read about it. In short: In enzymology, a methylated-DNA-[protein]-cysteine S-methyltransferase (EC 2.1.1.63) is an enzyme that catalyzes the chemical reaction DNA (containing 6-O-methylguanine) + protein L-cysteine ⇌ {\displaystyle \rightleftharpoons } DNA (without 6-O-methylguanine) + protein S-methyl-L-cysteine Thus, the two substrates of this enzyme are DNA containing 6-O-methylguanine and protein L-cysteine, whereas its two products ar…

Key takeaways

Methylated-DNA—(protein)-cysteine S-methyltransferase belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Methylated-DNA—(protein)-cysteine S-methyltransferase to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Methylated-DNA—(protein)-cysteine S-methyltransferase from memory before moving on to harder problems.

Reference excerpt

In enzymology, a methylated-DNA-[protein]-cysteine S-methyltransferase (EC 2.1.1.63) is an enzyme that catalyzes the chemical reaction

DNA (containing 6-O-methylguanine) + protein L-cysteine ⇌ {\displaystyle \rightleftharpoons } DNA (without 6-O-methylguanine) + protein S-methyl-L-cysteine Thus, the two substrates of this enzyme are DNA containing 6-O-methylguanine and protein L-cysteine, whereas its two products are DNA and protein S-methyl-L-cysteine. The S-methyl-L-cysteine residue irreversibly inactivates the protein, allowing only one transfer for each protein. This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is DNA-6-O-methylguanine:[protein]-L-cysteine S-methyltransferase.

Structural studies As of late 2007, 11 structures have been solved for this class of enzymes, with PDB accession codes PDB: 1EH6, PDB: 1EH7, PDB: 1EH8, PDB: 1MGT, PDB: 1QNT, PDB: 1SFE, PDB: 1T38, PDB: 1T39, PDB: 1WRJ, PDB: 1YFH, and PDB: 2G7H.

References

Foote RS, Mitra S, Pal BC (1980). "Demethylation of O6-methylguanine in a synthetic DNA polymer by an inducible activity in Escherichia coli". Biochem. Biophys. Res. Commun. 97 (2): 654–9. doi:10.1016/0006-291X(80)90314-9. PMID 7008792. Olsson M, Lindahl T (1980). "Repair of alkylated DNA in Escherichia coli. Methyl group transfer from O6-methylguanine to a protein cysteine residue". J. Biol. Chem. 255 (22): 10569–71. doi:10.1016/S0021-9258(19)70341-X. PMID 7000780. Pegg AE, Byers TL (1992). "Repair of DNA containing O6-alkylguanine". FASEB J. 6 (6): 2302–10. doi:10.1096/fasebj.6.6.1544541. PMID 1544541. S2CID 41168151.

Worked examples

Example 1 — a first encounter with Methylated-DNA—(protein)-cysteine S-methyltransferase

Start with the simplest possible case. Write down what Methylated-DNA—(protein)-cysteine S-methyltransferase claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, 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 Methylated-DNA—(protein)-cysteine S-methyltransferase 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 Methylated-DNA—(protein)-cysteine S-methyltransferase 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 Methylated-DNA—(protein)-cysteine S-methyltransferase

In research: Methylated-DNA—(protein)-cysteine S-methyltransferase appears in biology 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 Methylated-DNA—(protein)-cysteine S-methyltransferase 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: Methylated-DNA—(protein)-cysteine S-methyltransferase is common in secondary-school and first-year university syllabi. It links to neighbouring topics EC 2.1.1, EC 2.1 stubs, Enzymes of known structure, so understanding it makes those chapters shorter.
In everyday life: Look for Methylated-DNA—(protein)-cysteine S-methyltransferase 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 Methylated-DNA—(protein)-cysteine S-methyltransferase in 20 minutes

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Frequently asked questions

What is Methylated-DNA—(protein)-cysteine S-methyltransferase in simple terms?

In enzymology, a methylated-DNA-[protein]-cysteine S-methyltransferase (EC 2.1.1.63) is an enzyme that catalyzes the chemical reaction DNA (containing 6-O-methylguanine) + protein L-cysteine ⇌ {\displaystyle \rightleftharpoons } DNA (without 6-O-methylguanine) + protein S-methyl-L-cysteine Thus, th…

Why does Methylated-DNA—(protein)-cysteine S-methyltransferase matter?

Because it connects several biology 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 Methylated-DNA—(protein)-cysteine S-methyltransferase?

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 Methylated-DNA—(protein)-cysteine S-methyltransferase.