| Tetrahydromethanopterin | |
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| Identifiers | |
| PubChem | 5459995 |
| ChemSpider | 4573696 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C30H45N6O16P |
| Molar mass | 776.682661 |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
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.[1]
Tetrahydrosarcinapterin (THSPT, H4SPT) is a modified form of THMPT, wherein a glutamyl group linked to the 2-hydroxyglutaric acid terminus.
N-Formylmethanofuran donates the C1 group to the N5 site of the pterin to give the formyl- THMPT.[2] The formyl group subsequently condenses intramolecularly to give methenyl- THMPT+, which is then reduced to methylene- THMPT.[3] Methylene- MPT is subsequently converted, using coenzyme F420 as the electron source, to methyl- THMPT, catalyzed by F420-dependent methylene- THMPT reductase. Methyl- THMPT is the methyl donor to coenzyme M, a conversion mediated by methyl- THMPT:coenzyme M methyl-transferase.[1]
THMPT is related to the better known tetrahydrofolic acid (THFA, H4FA). The most important difference between THMPT and THFA is that THFA has an electron-withdrawing carbonyl group on the phenyl ring. As a consequence, methenyl- THMPT is more difficult to reduce than methenyl- THFA. Reduction is effected by a so-called iron-sulfur cluster free hydrogenase.[3] The cumbersome name distinguishes this hydrogenase from the so-called Fe-only hydrogenases that do contain Fe-S cluster.
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