coenzyme B

{{chembox

| Verifiedfields = changed

| verifiedrevid = 464184867

| ImageFile=Coenzyme B (CoB).svg

| ImageSize=

| ImageFile2=Coenzyme B 3D BS.png

| ImageSize2=

| IUPACName=2-[(7-mercapto-1-oxoheptyl)amino]-3-phosphonooxybutanoic acid

| OtherNames=

|Section1={{Chembox Identifiers

| InChI = 1/C11H22NO7PS/c1-8(19-20(16,17)18)10(11(14)15)12-9(13)6-4-2-3-5-7-21/h8,10,21H,2-7H2,1H3,(H,12,13)(H,14,15)(H2,16,17,18)/t8-,10-/m1/s1

| InChIKey = JBJSVEVEEGOEBZ-PSASIEDQBT

| InChI1 = 1/C11H22NO7PS/c1-8(19-20(16,17)18)10(11(14)15)12-9(13)6-4-2-3-5-7-21/h8,10,21H,2-7H2,1H3,(H,12,13)(H,14,15)(H2,16,17,18)

| InChIKey1 = JBJSVEVEEGOEBZ-UHFFFAOYAG

| SMILES1 = O=C(NC(C(=O)O)C(OP(=O)(O)O)C)CCCCCCS

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/C11H22NO7PS/c1-8(19-20(16,17)18)10(11(14)15)12-9(13)6-4-2-3-5-7-21/h8,10,21H,2-7H2,1H3,(H,12,13)(H,14,15)(H2,16,17,18)

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = JBJSVEVEEGOEBZ-UHFFFAOYSA-N

| CASNo_Ref = {{cascite|correct|CAS}}

| CASNo=104302-77-4

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = 9GS022ISQL

| PubChem=350

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 343

| SMILES = O=C(N[C@@H](C(=O)O)[C@H](OP(=O)(O)O)C)CCCCCCS

}}

|Section2={{Chembox Properties

| Formula={{chem|C|11|H|22|NO|7|PS}}

| MolarMass=343.333641

| Appearance=

| Density=

| MeltingPt=

| BoilingPt=

| Solubility=

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|Section3={{Chembox Hazards

| MainHazards=

| FlashPt=

| AutoignitionPt =

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Coenzyme B is a coenzyme required for redox reactions in methanogens. The full chemical name of coenzyme B is 7-mercaptoheptanoylthreoninephosphate.{{cite journal |vauthors=Noll KM, Rinehart KL, Tanner RS, Wolfe RS |title=Structure of component B (7-mercaptoheptanoylthreonine phosphate) of the methylcoenzyme M methylreductase system of Methanobacterium thermoautotrophicum |journal= Proceedings of the National Academy of Sciences|volume=83 |issue=12 |pages=4238–42 |year=1986 |pmid=3086878 |doi=10.1073/pnas.83.12.4238 |pmc=323707|bibcode=1986PNAS...83.4238N |doi-access=free }} The molecule contains a thiol, which is its principal site of reaction.

Coenzyme B reacts with 2-methylthioethanesulfonate (methyl-Coenzyme M, abbreviated {{chem|CH|3|–S–CoM}}), to release methane in methanogenesis:{{cite journal |author=Thauer RK |title=Biochemistry of methanogenesis: a tribute to Marjory Stephenson. 1998 Marjory Stephenson Prize Lecture |journal=Microbiology |volume=144 |issue=Pt 9 |pages=2377–406 |date=September 1998 |pmid=9782487 |doi=10.1099/00221287-144-9-2377 |doi-access=free }}

:{{chem|link=coenzyme M|CH|3|–S–CoM}} + HS–CoB → {{chem|CH|4}} + 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:{{cite journal |vauthors=Heim S, Künkel A, Thauer RK, Hedderich R |title=Thiol:fumarate reductase (Tfr) from Methanobacterium thermoautotrophicum—identification of the catalytic sites for fumarate reduction and thiol oxidation |journal= European Journal of Biochemistry|volume=253 |issue=1 |pages=292–9 |date=April 1998 |pmid=9578488 |doi=10.1046/j.1432-1327.1998.2530292.x|doi-access=free }}

:HS–CoM + HS–CoB + ⁻{{chem|O|2|CCH{{=}}CHCO|2|-}} → ⁻{{chem|O|2|CCH|2|–CH|2|CO|2|-}} + CoB–S–S–CoM