Methanogens are microorganisms that produce methane as a metabolic byproduct in hypoxic conditions. They are prokaryotic and belong to the domain Archaea. All known methanogens are members of the archaeal phylum Euryarchaeota. Methanogens are common in wetlands, where they are responsible for marsh gas, and can occur in the digestive tracts of animals including ruminants and humans, where they are responsible for the methane content of belching and flatulence. In marine sediments, the biological production of methane, termed methanogenesis, is generally confined to where sulfates are depleted below the top layers. Methanogenic archaea populations play an indispensable role in anaerobic wastewater treatments. Other methanogens are extremophiles, found in environments such as hot springs and submarine hydrothermal vents as well as in the "solid" rock of Earth's crust, kilometers below the surface.
Tetrahydromethanopterin 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.
Coenzyme B is a coenzyme required for redox reactions in methanogens. The full chemical name of coenzyme B is 7-mercaptoheptanoylthreoninephosphate. The molecule contains a thiol, which is its principal site of reaction.
5,10-Methylenetetrahydrofolate (N5,N10-Methylenetetrahydrofolate; 5,10-CH2-THF) is cofactor in several biochemical reactions. It exists in nature as the diastereoisomer [6R]-5,10-methylene-THF.
In enzymology, a 3-methyl-2-oxobutanoate dehydrogenase (ferredoxin) (EC 1.2.7.7) is an enzyme that catalyzes the chemical reaction
The 5,10-methenyltetrahydromethanopterin hydrogenase, the so-called iron-sulfur cluster-free hydrogenase, is an enzyme found in methanogenic archea such as Methanothermobacter marburgensis. It was discovered and first characterized by the Thauer group at the Max Planck Institute in Marburg. Hydrogenases are enzymes that either reduce protons or oxidize molecular dihydrogen.
In enzymology, a coenzyme F420 hydrogenase (EC 1.12.98.1) is an enzyme that catalyzes the chemical reaction
In enzymology, a CoB—CoM heterodisulfide reductase (EC 1.8.98.1) is an enzyme that catalyzes the chemical reaction
In enzymology, a methylenetetrahydrofolate dehydrogenase (NADP+) (EC 1.5.1.5) is an enzyme that catalyzes the chemical reaction
In enzymology, a methylenetetrahydromethanopterin dehydrogenase (EC 1.5.98.1) is an enzyme that catalyzes the chemical reaction
In enzymology, coenzyme-B sulfoethylthiotransferase, also known as methyl-coenzyme M reductase (MCR) or most systematically as 2-(methylthio)ethanesulfonate:N-(7-thioheptanoyl)-3-O-phosphothreonine S-(2-sulfoethyl)thiotransferase is an enzyme that catalyzes the final step in the formation of methane. It does so by combining the hydrogen donor coenzyme B and the methyl donor coenzyme M. Via this enzyme, most of the natural gas on earth was produced. Ruminants produce methane because their rumens contain methanogenic prokaryotes (Archaea) that encode and express the set of genes of this enzymatic complex.
Coenzyme F420 or 8-hydroxy-5-deazaflavin is a coenzyme (sometimes called a cofactor) involved in redox reactions in methanogens, in many Actinomycetota, and sporadically in other bacterial lineages. It is a flavin derivative with an absorption maximum at 420 nm—hence its name. The coenzyme is a substrate for coenzyme F420 hydrogenase, 5,10-methylenetetrahydromethanopterin reductase and methylenetetrahydromethanopterin dehydrogenase.
In enzymology, a methenyltetrahydromethanopterin cyclohydrolase (EC 3.5.4.27) is an enzyme that catalyzes the chemical reaction
In enzymology, a formylmethanofuran-tetrahydromethanopterin N-formyltransferase is an enzyme that catalyzes the chemical reaction
F430 is the cofactor (sometimes called the coenzyme) of the enzyme methyl coenzyme M reductase (MCR). MCR catalyzes the reaction EC 2.8.4.1 that releases methane in the final step of methanogenesis:
Malate dehydrogenase (NAD(P)+) (EC 1.1.1.299, MdH II, NAD(P)+-dependent malate dehyrogenase) is an enzyme with systematic name (S)-malate:NAD(P)+ oxidoreductase. This enzyme catalyses the following chemical reaction
Glucose-6-phosphate dehydrogenase (coenzyme-F420) is an enzyme with systematic name D-glucose-6-phosphate:F420 1-oxidoreductase. This enzyme catalyses the following chemical reaction
(Methyl-Co methanol-specific corrinoid protein):coenzyme M methyltransferase is an enzyme with systematic name methylated methanol-specific corrinoid protein:coenzyme M methyltransferase. This enzyme catalyses the following chemical reaction
Dimethylamine-corrinoid protein Co-methyltransferase is an enzyme with systematic name dimethylamine:5-hydroxybenzimidazolylcobamide Co-methyltransferase. This enzyme catalyses the following chemical reaction
In enzymology, a formylmethanofuran dehydrogenase (EC 1.2.99.5) is an enzyme that catalyzes the chemical reaction:
