MetaCyc Enzyme: methenyl-H4MPT cyclohydrolase

Gene: mch Accession Number: G-353 (MetaCyc)

Species: Methanothermobacter thermautotrophicus

Subunit composition of methenyl-H4MPT cyclohydrolase = [Mch]2

Locations: cytosol

Molecular Weight of Polypeptide: 34.098 kD (from nucleotide sequence) [Bairoch93a ]

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

GO Terms:

Cellular Component: GO:0005829 - cytosol

Enzymatic reaction of: methenyl-H4MPT cyclohydrolase

Synonyms: methenyltetrahydromethanopterin cyclohydrolase, N5,N10-methenyltetrahydromethanopterin cyclohydrolase, 5,10-methenyltetrahydromethanopterin 10-hydrolase (decyclizing)

EC Number:

5,10-methenyltetrahydromethanopterin + H2O <=> 5-formyl-tetrahydromethanopterin + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

This reaction is reversible.

In Pathways: superpathway of methanogenesis , methanogenesis from H2 and CO2

Methenyl-H4MPT cyclohydrolase catalyzes the third reaction in methanogenesis from CO2. In the hydrolytic direction it produces a 5-formyl derivative as contrasted to the tetrahydrofolate enzymes which produce a 10-formyl derivative. [DiMarco86, Donnelly85, Vaupel96, Thauer98]

Activators (Unknown Mechanism): Mg2+ [DiMarco86]

Inhibitors (Unknown Mechanism): 10-formyltetrahydromethanopterin [DiMarco86] , Mn2+ [DiMarco86]


Bairoch93a: Bairoch A, Boeckmann B (1993). "The SWISS-PROT protein sequence data bank, recent developments." Nucleic Acids Res. 21:3093-3096. PMID: 8332529

DiMarco86: DiMarco AA, Donnelly MI, Wolfe RS (1986). "Purification and properties of the 5,10-methenyltetrahydromethanopterin cyclohydrolase from Methanobacterium thermoautotrophicum." J Bacteriol 1986;168(3);1372-7. PMID: 3782039

Donnelly85: Donnelly MI, Escalante-Semerena JC, Rinehart KL, Wolfe RS (1985). "Methenyl-tetrahydromethanopterin cyclohydrolase in cell extracts of Methanobacterium." Arch Biochem Biophys 1985;242(2);430-9. PMID: 4062290

Thauer98: Thauer RK (1998). "Biochemistry of methanogenesis: a tribute to Marjory Stephenson." Microbiology 1998;144 ( Pt 9);2377-406. PMID: 9782487

Vaupel96: Vaupel M, Dietz H, Linder D, Thauer RK (1996). "Primary structure of cyclohydrolase (Mch) from Methanobacterium thermoautotrophicum (strain Marburg) and functional expression of the mch gene in Escherichia coli." Eur J Biochem 1996;236(1);294-300. PMID: 8617278

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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