Coenzyme B

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Coenzyme B
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IUPAC name 2-[(7-mercapto-1-oxoheptyl)amino]-3-phosphonooxybutanoic acid
Identifiers
CAS number
PubChem 350
SMILES CC(C(C(=O)O)NC(=O)CCCCCCS)OP(=O)(O)O
Properties
Molecular formula C11H22NO7PS
Molar mass 343.333641
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Coenzyme B is a coenzyme required for redox reactions in methanogens. The full chemical name of coenzyme B is 7-thioheptanoylthreoninephosphate.[1] The molecule contains a thiol, which is its principal site of reaction.

Coenzyme B reacts with 2-methylthioethanesulfonate, abbreviated CH3-S-CoM, to release methane in methanogenesis:[2]

CH3-S-CoM + HS-CoB → CH4 + 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 fumarate to succinate, catalyzed by fumarate reductase:[3]

CH3-S-CoM + HS-CoB -O2CCH=CHCO2--O2CCH2-CH2CO2- + CoB-S-S-CoM

References

  1. Noll KM, Rinehart KL, Tanner RS, Wolfe RS (1986). "Structure of component B (7-mercaptoheptanoylthreonine phosphate) of the methylcoenzyme M methylreductase system of Methanobacterium thermoautotrophicum". Proc. Natl. Acad. Sci. U.S.A. 83 (12): 4238–42. PMID 3086878. 
  2. Thauer, R. K., "Biochemistry of Methanogenesis: a Tribute to Marjory Stephenson", Microbiology, 1998, volume 144, pages 2377-2406.
  3. Heim, S.; Künkel, A.; Thauer, R. K.; Hedderich, R. “Thiol:fumarate Reductase (Tfr) from Methanobacterium thermoautotrophicum: Identification of the Catalytic Sites for Fumarate Reduction and Thiol Oxidation” European Journal of Biochemistry 1998, volume 253, pages 292-299.




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