Coenzyme-B sulfoethylthiotransferase
coenzyme-B sulfoethylthiotransferase | |||||||||
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Identifiers | |||||||||
EC number | 2.8.4.1 | ||||||||
Databases | |||||||||
IntEnz | IntEnz view | ||||||||
BRENDA | BRENDA entry | ||||||||
ExPASy | NiceZyme view | ||||||||
KEGG | KEGG entry | ||||||||
MetaCyc | metabolic pathway | ||||||||
PRIAM | profile | ||||||||
PDB structures | RCSB PDB PDBe PDBsum | ||||||||
Gene Ontology | AmiGO / EGO | ||||||||
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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.[1] 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 (e.g. cows) produce methane because their rumens contain methanogenic prokaryotes (Archaea)[2][3] that encode and express the set of genes of this enzymatic complex.
The enzyme has two active sites, each occupied by the nickel-containing F430 cofactor.[4]
- 2-(methylthio)ethanesulfonate (methyl-CoM) + N-(7-mercaptoheptanoyl)threonine 3-O-phosphate (coenzyme B) CoM-S-S-CoB + methane
Thus, the two substrates of this enzyme are 2-(methylthio)ethanesulfonate and N-(7-mercaptoheptanoyl)threonine 3-O-phosphate, whereas its two products are CoM-S-S-CoB and methane.
In some species, the enzyme reacts in reverse (a process called reverse methanogenesis), catalysing the anaerobic oxidation of methane, therefore removing it from the environment.[5] Such organisms are methanotrophs.
This enzyme belongs to the family of transferases, specifically those transferring alkylthio groups.
This enzyme participates in folate biosynthesis.[citation needed]
Structure
coenzyme-B sulfoethylthiotransferase is a protein complex made up of a pair of identical halves. Each half up of 3 subunits: α, β and γ,[6] also called McrA, McrB and McrG, respectively.
References
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ http://microbewiki.kenyon.edu/index.php/Bovine_Rumen#Methanogens
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Thauer, R. K., "Biochemistry of methanogenesis: a tribute to Marjory Stephenson", Microbiology, 1998, 144, 2377-2406. doi:10.1099/00221287-144-9-2377 PMID 9782487
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
Further reading
- Lua error in package.lua at line 80: module 'strict' not found.
- Lua error in package.lua at line 80: module 'strict' not found.
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