chemistry

Tetrahydromethanopterin

Tetrahydromethanopterin 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 Tetrahydromethanopterin rather than just read about it. In short: 5,6,7,8-Tetrahydromethanopterin (THMPT, H4MPT) is a coenzyme in methanogenesis. It is the carrier of the C1 group as it is reduced to the methyl level, before transferring to the coenzyme M.

Key takeaways

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

Reference excerpt

5,6,7,8-Tetrahydromethanopterin (THMPT, H4MPT) is a coenzyme in methanogenesis. It is the carrier of the C1 group as it is reduced to the methyl level, before transferring to the coenzyme M.

Structure The structure of H4MPT is analogous to that of tetrahydrofolate (THFA, H4folate). Both share a core derived from dihydropteroate (H2Pte), but where H4folate acid has a glutamyl tail attached to the 1' carbonyl group of H2Pte, H4MPT instead has a "a ribitol residue linked to ribose 5-phosphate and thence to hydroxyglutarate". The pteroate part also sees two additional chiral methyl groups: carbon #12 on the branch connecting it to the phenyl ring (position 11, corresponds to folate position 9) and carbon #13 on the pterin core (position 7 in both MPT and folate). The lack of a electron-withdrawing carbonyl group para to N10 increases the electron density at this 10-position. The pKa for this atom in H4MPT is -1.2, compared to +2.4 for H4folate. The biochemical redox potential E'0 is more negative in reactions that involve one-carbon units bound to this atom. In contrast, the chemical environment of N5 is largely unchanged as far as enthalpy is concerned. This difference has the effects including but not limited to:

Methenyl-THMPT (CH+-H4MPT) is more difficult to reduce than methenyl-THFA (CH+-H4folate). Reduction is effected by a so-called iron-sulfur cluster free hydrogenase. The cumbersome name distinguishes this hydrogenase from the other hydrogenases that do contain Fe-S cluster. Steric hinderince from the 11-methyl group may also play a role. The methylene of CH2-H4MPT exchanges more slowly with the formyl from formaldehyde compared to the analogous CH2-H4folate reaction. The epimerization of this methylene is also slower. Formyl (HCO)-H4MPT is thermodynamically able to spontaneously cyclize to CH2-H4MPT, unlike the folate analogos which requires energy input from ATP. Unlike in THF where the formyl group attaches to position 10, the formyl group attaches to position 5 on THMPT.

Biosynthesis Steps in the biosynthesis of methanopetrin include:

Variations There are numerous variations on H4MPT in archaea (bacteria tend to stick to the standard molecule):

Pyrococcus and Thermococcus have a poly-β3(l→4)-linked N-acetylglucosamine side chain instead of the hydroxyglutamic acid terminus. There can be 1–5 units. In (tetrahydro)sarcinapterin (H4SPT), a glutamyl group is linked to the 2-hydroxyglutaric acid terminus of MPT. This reaction is mediated by EC 6.3.2.33 tetrahydrosarcinapterin synthase. (H4)tatiopterin-0 differs from H4SPT by the lack of 7-methylation. Tatiopterin-1 has one more glutamyl group attached to the α carboxyl of the additional glutamyl. (H4)thermopterin differs from tatiopterin-0 by the addition of an electron-withdrawing phenyl group in the 3' position, ortho to the pterin part and meta to the ribulose chain. (H4)sulfopterin of Sulfolobus has neither methyl group. The molecule has only been characterized to the ribulose, with the rest being unknown.

Biochemical function

One-carbon carrier N-Formylmethanofuran donates the C1 group to the N5 site of the pterin to give the 5-formyl-THMPT (5-CHO-H4MPT). (This is different from THF, which tends to give 10-formyl-THF. The difference is due to the aforementioned local chemical difference.) The formyl group subsequently condenses intramolecularly to give 5,10-methenyl-THMPT+ (5,10-CH+-H4MPT), which is then reduced to 5,10-methylene-THMPT (5,10-CH2-H4MPT) by 5,10-methenyl-THMPT+ hydrogenase with H2 as the electron donor. 5,10-Methylene-MPT is subsequently converted, using coenzyme F420 as the electron source, to methyl-THMPT (5-CH3-H4MPT), catalyzed by F420-dependent methylene-THMPT reductase. 5-Methyl-THMPT is the methyl donor to coenzyme M, a conversion mediated by methyl-THMPT: coenzyme M methyltransferase. Like THF, the C1 transformations of THMPT can lead to acetyl-CoA as well as convert glycine to serine. It does not feed into purine metabolism, glycine production, or ketoglutarate production, however. Evidence for MPT participation in methionine synthesis is weak (as of 2000). Further genetic work has not identified a methyl-THMPT-using methionine synthase (though the split-MetE versions remain candidates) but has instead found many that use a corrinoid protein to carry the methyl group. In methanogens with the MesA synthase, the methyl group likely comes from the aforementioned methyl-THMPT: coenzyme M methyltransferase, so ultimately these organisms do obtain their methyl from methyl-THMPT. How (and whether) MPT relates to thymidylate biosynthesis is also unclear. Cell-free extracts of various archaea are able to convert dUMP to dTMP when given MPT (or sulfopterin fragments, in the case of Sulfolobus) and isotope-labeled formaldehyde, but no enzyme has been identified.

C2 N5,N10-(1,1-ethylene)H4MPT (5,10-ethylene-H4MPT) and N5-ethyl-H4MPT have been detected in Methanothermobacter marburgensis, indicating that H4MPT can also serve as a two-carbon carrier. Under standard conditions, H4MPT spontaneously reacts with acetaldehyde to yield ethylene-H4MPT. M. marburgensis lysate contains an enzyme that catalyzes this product's reduction to ethyl-H4MPT.

References

Worked examples

Example 1 — a first encounter with Tetrahydromethanopterin

Start with the simplest possible case. Write down what Tetrahydromethanopterin 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 Tetrahydromethanopterin 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 Tetrahydromethanopterin 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 Tetrahydromethanopterin

In research: Tetrahydromethanopterin 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 Tetrahydromethanopterin 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: Tetrahydromethanopterin is common in secondary-school and first-year university syllabi. It links to neighbouring topics Anilines, Coenzymes, Dicarboxylic acids, so understanding it makes those chapters shorter.
In everyday life: Look for Tetrahydromethanopterin 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Tetrahydromethanopterin” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Tetrahydromethanopterin in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tetrahydromethanopterin 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 Tetrahydromethanopterin out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Tetrahydromethanopterin in simple terms?

5,6,7,8-Tetrahydromethanopterin (THMPT, H4MPT) is a coenzyme in methanogenesis. It is the carrier of the C1 group as it is reduced to the methyl level, before transferring to the coenzyme M.

Why does Tetrahydromethanopterin 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 Tetrahydromethanopterin?

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 Tetrahydromethanopterin.