Coenzyme B is a coenzyme required for redox reactions in . The full chemical name of coenzyme B is 7-mercaptoheptanoylthreoninephosphate.
Coenzyme B reacts with 2-methylthioethanesulfonate (methyl-Coenzyme M, abbreviated ), to release methane in methanogenesis:
- + HS–CoB → + CoB–S–S–CoM
This conversion is catalyzed by the
enzyme methyl coenzyme M reductase, which contains cofactor F430 as the
prosthetic group.
A related conversion that utilizes both HS-CoB and HS-CoM is the reduction of fumaric acid to succinic acid, catalysis by fumarate reductase:
- HS–CoM + HS–CoB + − → − + CoB–S–S–CoM
Importance of coenzyme B in methanogenesis
Coenzyme B is an important component in the terminal step of methane biogenesis.
It acts as a two electron-donor to reduce coenzyme M (methyl-coenzyme) into two molecules a methane and a heterodisulfide.
Two separate experiments that were performed, one with coenzyme B and other without coenzyme B, indicated that using coenzyme B before the formation of the methane molecule, results in a more efficient and consistent bond cleavage.
