In enzymology, a CoB—CoM heterodisulfide reductase () is an enzyme that catalyzes the chemical reaction coenzyme B + coenzyme M + methanophenazine N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine + dihydromethanophenazine The 3 substrates of this enzyme are coenzyme B, coenzyme M, and methanophenazine, whereas its two products are [[N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine]] and dihydromethanophenazine. This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with other, known, acceptors. The systematic name of this enzyme class is coenzyme B:coenzyme M:methanophenazine oxidoreductase. Other names in common use include heterodisulfide reductase, and soluble heterodisulfide reductase. This enzyme participates in folate biosynthesis. References EC 1.8.98 Enzymes of unknown structure