Methyl-coenzyme M reductase (MCR) is an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 that occurs in archaea

Archaea

The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...

. This enzyme catalyzes

Catalysis

Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....

 the formation of methane

Methane

Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

 by combining the hydrogen donor coenzyme B

Coenzyme B

Coenzyme B is a coenzyme required for redox reactions in methanogens. The full chemical name of coenzyme B is 7-mercaptoheptanoylthreoninephosphate...

 and the methyl donor coenzyme M

Coenzyme M

Coenzyme M is a coenzyme required for methyl-transfer reactions in the metabolism of methanogens. The coenzyme is an anion with the formula . It is named 2-mercaptoethanesulfonate and abbreviated HS–CoM. The cation is unimportant, but the sodium salt is most available...

. Via this enzyme, most of the natural gas on earth was produced. Ruminant

Ruminant

A ruminant is a mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first compartment of the stomach, principally through bacterial actions, then regurgitating the semi-digested mass, now known as cud, and chewing it again...

s (e.g. cows) produce methane because their rumens contain methanogenic bacteria that also rely on this enzyme.

The enzyme has two active site

Active site

In biology the active site is part of an enzyme where substrates bind and undergo a chemical reaction. The majority of enzymes are proteins but RNA enzymes called ribozymes also exist. The active site of an enzyme is usually found in a cleft or pocket that is lined by amino acid residues that...

s, each occupied by the nickel

Nickel

Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

-containing F₄₃₀

Cofactor F430

F430 is the prosthetic group of the enzyme methyl coenzyme M reductase. It is found only in methanogenic Archaea. This enzyme catalyzes the release of methane in the final step of methanogenesis:-Corphin in context:...

 cofactor

Cofactor (biochemistry)

A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....

. This conversion is symbolically written as:

CH₃-S-CoM + HS-CoB → CH₄ + CoB-S-S-CoM

The IUBMB Enzyme Nomenclature accepted name is coenzyme-B sulfoethylthiotransferase

Coenzyme-B sulfoethylthiotransferase

In enzymology, a coenzyme-B sulfoethylthiotransferase is an enzyme that catalyzes the chemical reactionThus, the two substrates of this enzyme are 2-ethanesulfonate and N-threonine 3-O-phosphate, whereas its two products are CoM-S-S-CoB and methane.This enzyme belongs to the family of...

.