EC                 Enzyme                                 

cyanocobalamin reductase (cyanide-eliminating);
MMACHC (gene name);
cyanocobalamin reductase;
cyanocobalamin reductase (NADPH, cyanide-eliminating);
cyanocobalamin reductase (NADPH, CN-eliminating);
NADPH:cyanocob(III)alamin oxidoreductase (cyanide-eliminating);
cob(I)alamin, cyanide:NADP+ oxidoreductase
Oxidizing metal ions;
With NAD+ or NADP+ as acceptor
BRITE hierarchy
cob(II)alamin, hydrogen cyanide:NADP+ oxidoreductase
2 cob(II)alamin-[cyanocobalamin reductase] + 2 hydrogen cyanide + NADP+ = 2 cyanocob(III)alamin + 2 [cyanocobalamin reductase] + NADPH + H+ [RN:R02999]
cob(II)alamin-[cyanocobalamin reductase];
hydrogen cyanide [CPD:C01326];
NADP+ [CPD:C00006]
cyanocob(III)alamin [CPD:C02823];
[cyanocobalamin reductase];
NADPH [CPD:C00005];
H+ [CPD:C00080]
The mammalian enzyme, which is cytosolic, can bind internalized cyanocobalamin and process it to cob(II)alamin by removing the upper axial ligand. The product remains bound to the protein, which, together with its interacting partner MMADHC, transfers it directly to downstream enzymes involved in adenosylcobalamin and methylcobalamin biosynthesis. In addition to its decyanase function, the mammalian enzyme also catalyses an entirely different chemical reaction with alkylcobalamins, using the thiolate of glutathione for nucleophilic displacement, generating cob(I)alamin and the corresponding glutathione thioether (cf. EC, alkylcobalamin dealkylase).
EC created 1989 as EC, transferred 2002 to EC, modified 2018
ec00860  Porphyrin and chlorophyll metabolism
ec01100  Metabolic pathways
K14618  cyanocobalamin reductase (cyanide-eliminating) / alkylcobalamin dealkylase
HSA: 25974(MMACHC)
PTR: 469180(MMACHC)
PPS: 100968335(MMACHC)
GGO: 101152807(MMACHC)
PON: 100455100(MMACHC)
NLE: 100580574(MMACHC)
MCC: 706247(MMACHC)
MCF: 102121304(MMACHC)
CSAB: 103224912(MMACHC)
RRO: 104662137(MMACHC)
RBB: 108535651(MMACHC)
CJC: 100399324(MMACHC)
SBQ: 101027482(MMACHC)
MMU: 67096(Mmachc)
MCAL: 110293555(Mmachc)
MPAH: 110323588(Mmachc)
RNO: 313520(Mmachc)
MUN: 110546536(Mmachc)
CGE: 100751045(Mmachc)
NGI: 103737785(Mmachc)
HGL: 101709397(Mmachc)
OCU: 100347413(MMACHC)
TUP: 102472726(MMACHC)
CFA: 482514(MMACHC)
VVP: 112914783(MMACHC)
AML: 100466484(MMACHC)
UMR: 103670776(MMACHC)
UAH: 113254743(MMACHC)
ORO: 101379031(MMACHC)
FCA: 101090955(MMACHC)
PTG: 102954225(MMACHC)
PPAD: 109266970(MMACHC)
AJU: 106970243(MMACHC)
BTA: 513433(MMACHC)
BOM: 102277584(MMACHC)
BIU: 109556357(MMACHC)
BBUB: 102401472(MMACHC)
CHX: 102183931(MMACHC)
OAS: 101120707(MMACHC)
SSC: 100513159(MMACHC)
CFR: 102509232(MMACHC)
CDK: 105090870(MMACHC)
BACU: 103014111(MMACHC)
LVE: 103075700(MMACHC)
OOR: 101274733(MMACHC)
DLE: 111175748(MMACHC)
PCAD: 102979216(MMACHC)
ECB: 100065336(MMACHC)
EPZ: 103551877(MMACHC)
EAI: 106826139(MMACHC)
MYB: 102260677(MMACHC)
MYD: 102764382(MMACHC)
MNA: 107526768(MMACHC)
HAI: 109375517(MMACHC)
DRO: 112314606(MMACHC)
PALE: 102888849(MMACHC)
RAY: 107506891(MMACHC)
MJV: 108385733(MMACHC)
LAV: 100673499(MMACHC)
TMU: 101353030
MDO: 100024700(MMACHC)
SHR: 100914568(MMACHC)
PCW: 110209280(MMACHC)
OAA: 100077154(MMACHC)
GGA: 424597(MMACHC)
MGP: 100547376(MMACHC)
CJO: 107317442(MMACHC)
NMEL: 110402950(MMACHC)
APLA: 101804029(MMACHC)
ACYG: 106033094(MMACHC)
TGU: 105759460(MMACHC)
LSR: 110469630(MMACHC)
SCAN: 103815175(MMACHC)
GFR: 102038500(MMACHC)
FAB: 101815080(MMACHC)
PHI: 102110636(MMACHC)
PMAJ: 107208008(MMACHC)
CCAE: 111933112(MMACHC)
CCW: 104695241(MMACHC)
ETL: 114062118(MMACHC)
FPG: 101914760(MMACHC)
FCH: 102058033(MMACHC)
CLV: 102088492(MMACHC)
EGZ: 104126262(MMACHC)
NNI: 104015417(MMACHC)
ACUN: 113482722(MMACHC)
PADL: 103919135(MMACHC)
AAM: 106485930(MMACHC)
ASN: 102383499(MMACHC)
AMJ: 102560477(MMACHC)
PSS: 102459461(MMACHC)
CMY: 102936214(MMACHC)
CPIC: 101952441(MMACHC)
ACS: 100552851(mmachc)
PVT: 110073759(MMACHC)
PBI: 103063544(MMACHC)
PMUR: 107283422(MMACHC)
TSR: 106548837(MMACHC)
PMUA: 114599088(MMACHC)
GJA: 107107920(MMACHC)
XLA: 100127331(mmachc.L)
XTR: 549685(mmachc)
NPR: 108800338(MMACHC)
DRE: 555267(mmachc)
SRX: 107757670(mmachc)
SANH: 107653140(mmachc)
SGH: 107565041(mmachc)
CCAR: 109051604(mmachc)
IPU: 100528283(mmachc)
PHYP: 113546876(mmachc)
AMEX: 103032715(mmachc)
EEE: 113591323(mmachc)
TRU: 101073402(mmachc)
LCO: 104926001(mmachc)
NCC: 104967760(mmachc)
MZE: 101475866(mmachc)
ONL: 100705297(mmachc)
OLA: 101155593(mmachc)
XMA: 102223263(mmachc)
XCO: 114150362(mmachc)
PRET: 103463749(mmachc)
CVG: 107096364(mmachc)
NFU: 107396398(mmachc)
KMR: 108230696(mmachc)
ALIM: 106533393(mmachc)
AOCE: 111564984(mmachc)
CSEM: 103376733(mmachc)
POV: 109625330(mmachc)
LCF: 108879008(mmachc)
SDU: 111231994(mmachc)
SLAL: 111653738(mmachc)
HCQ: 109532243(mmachc)
BPEC: 110154834(mmachc)
MALB: 109974876(mmachc)
SASA: 100196847(mmachc)
OTW: 112251067(mmachc)
SALP: 111975270(mmachc)
ELS: 105011679(mmachc)
SFM: 108923522(mmachc)
PKI: 111834817(mmachc)
LCM: 102353117(MMACHC)
CMK: 103182780(mmachc)
RTP: 109926396(mmachc)
CIN: 100181296
SPU: 575015
APLC: 110989375
SKO: 100368262
FCD: 110861518
DPTE: 113791070
CEL: CELE_ZK546.17(cblc-1)
CBR: CBG02282(Cbr-mdt-4)
TSP: Tsp_00699
PCAN: 112574267
CRG: 105331412
MYI: 110443657
LAK: 106178486
SHX: MS3_11205
EPA: 110237339
ADF: 107347741
AMIL: 114956024
PDAM: 113667854
SPIS: 111334144
DGT: 114526387
HMG: 100212172
AQU: 100641773
 » show all
1  [PMID:3134526]
Watanabe F, Oki Y, Nakano Y, Kitaoka S.
Occurrence and characterization of cyanocobalamin reductase (NADPH; CN-eliminating) involved in decyanation of cyanocobalamin in Euglena gracilis.
J Nutr Sci Vitaminol (Tokyo) 34:1-10 (1988)
2  [PMID:18779575]
Kim J, Gherasim C, Banerjee R
Decyanation of vitamin B12 by a trafficking chaperone.
Proc Natl Acad Sci U S A 105:14551-4 (2008)
3  [PMID:21697092]
Koutmos M, Gherasim C, Smith JL, Banerjee R
Structural basis of multifunctionality in a vitamin B12-processing enzyme.
J Biol Chem 286:29780-7 (2011)
4  [PMID:23270877]
Mah W, Deme JC, Watkins D, Fung S, Janer A, Shoubridge EA, Rosenblatt DS, Coulton JW
Subcellular location of MMACHC and MMADHC, two human proteins central to intracellular vitamin B(12) metabolism.
Mol Genet Metab 108:112-8 (2013)
Other DBs
ExplorEnz - The Enzyme Database:
IUBMB Enzyme Nomenclature:
ExPASy - ENZYME nomenclature database:
BRENDA, the Enzyme Database:
CAS: 131145-00-1

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