KEGG   ENZYME: 4.4.1.2Help
Entry
EC 4.4.1.2                  Enzyme                                 

Name
homocysteine desulfhydrase;
homocysteine desulfurase;
L-homocysteine hydrogen-sulfide-lyase (deaminating)
Class
Lyases;
Carbon-sulfur lyases;
Carbon-sulfur lyases (only sub-subclass identified to date)
BRITE hierarchy
Sysname
L-homocysteine hydrogen-sulfide-lyase (deaminating; 2-oxobutanoate-forming)
Reaction(IUBMB)
L-homocysteine + H2O = hydrogen sulfide + NH3 + 2-oxobutanoate (overall reaction) [RN:R01283];
(1a) L-homocysteine = hydrogen sulfide + 2-aminobut-2-enoate [RN:R08633];
(1b) 2-aminobut-2-enoate = 2-iminobutanoate (spontaneous);
(1c) 2-iminobutanoate + H2O = 2-oxobutanoate + NH3 (spontaneous)
Reaction(KEGG)
Substrate
L-homocysteine [CPD:C00155];
H2O [CPD:C00001];
2-aminobut-2-enoate [CPD:C17234];
2-iminobutanoate [CPD:C20905]
Product
hydrogen sulfide [CPD:C00283];
NH3 [CPD:C00014];
2-oxobutanoate [CPD:C00109];
2-aminobut-2-enoate [CPD:C17234];
2-iminobutanoate [CPD:C20905]
Comment
A pyridoxal-phosphate protein. The enzyme cleaves a carbon-sulfur bond, releasing hydrogen sulfide and an unstable enamine product that tautomerizes to an imine form, which undergoes a hydrolytic deamination to form 2-oxobutanoate and ammonia. The latter reaction, which can occur spontaneously, can also be catalysed by EC 3.5.99.10, 2-iminobutanoate/2-iminopropanoate deaminase
History
EC 4.4.1.2 created 1961
Pathway
ec00920  Sulfur metabolism
Orthology
K17217  cystathionine gamma-lyase / homocysteine desulfhydrase
Genes
PFE: PSF113_4197
PBC: CD58_21630
BSU: BSU27250(yrhB)
BSR: I33_2767(yrhB)
BSL: A7A1_0367
BSH: BSU6051_27250(mccB)
BSY: I653_12940
BSUT: BSUB_02907(mccB)
BSUL: BSUA_02907(mccB)
BSUS: Q433_14680
BSS: BSUW23_13180(mccB)
BST: GYO_2965(yrhB)
BSO: BSNT_09119(yrhB)
BSQ: B657_27250(mccB)
BSX: C663_2562(mccB)
BLI: BL02018(yrhB)
BLD: BLi02853(mccB)
BLH: BaLi_c29540(mccB)
BAY: RBAM_024350(yrhB)
BAQ: BACAU_2449(yrhB)
BYA: BANAU_2593(yrhB)
BAMP: B938_12585
BAML: BAM5036_2375(mccB)
BAMA: RBAU_2572(mccB)
BAMN: BASU_2378(mccB)
BAMB: BAPNAU_1127(yrhB)
BAMT: AJ82_13760
BAMY: V529_27190(yrhB)
BMP: NG74_02557(mccB)
BAO: BAMF_2533(mccB)
BAZ: BAMTA208_13370(mccB)
BQL: LL3_02811(mccB)
BXH: BAXH7_02735(yrhB)
BAMI: KSO_007200
BAMC: U471_25270
BAMF: U722_13215
BATR: TD68_10400
BAN: BA_4600
BAR: GBAA_4600
BAT: BAS4268
BAI: BAA_4620
BANT: A16_45980
BANR: A16R_60345
BANS: BAPAT_4415
BANV: DJ46_3277(mccB)
BCE: BC4366
BCA: BCE_4454(metC)
BCZ: BCE33L4116(metC)
BCQ: BCQ_4156(metC)
BCX: BCA_4484
BAL: BACI_c43580(metC2)
BNC: BCN_4282
BCF: bcf_21745
BCER: BCK_13335
BTK: BT9727_4105(metC)
BTL: BALH_3957(metC)
BTT: HD73_4680
BTHI: BTK_23050
BTM: MC28_3663
BTG: BTB_c45120(mccB)
BTI: BTG_27215
BTW: BF38_126(mccB)
BWW: bwei_0567(mccB)
BMYC: DJ92_1469(mccB)
BMYO: BG05_1654
BCL: ABC1945
BPU: BPUM_2360
BPUM: BW16_12815
BPUS: UP12_11885
BMQ: BMQ_4594(mccB)
BMD: BMD_4580(mccB)
BAG: Bcoa_1961
BCOA: BF29_1572(mccB)
BJS: MY9_2706
BMET: BMMGA3_12170(mccB)
BACW: QR42_11960
BACP: SB24_16520
BACB: OY17_15455
BACY: QF06_11815
BACL: BS34A_29730(yrhB)
BALM: BsLM_2694
BEO: BEH_16500
BGY: BGLY_3172(mccB)
OIH: OB1109(metC)
GKA: GK2540
GTN: GTNG_2473
GGH: GHH_c26140(mcc)
GEA: GARCT_02594(mccB)
AFL: Aflv_0761
AAMY: GFC30_2789
HHD: HBHAL_2023(mccB)
SAU: SA0419(metB)
SAV: SAV0460(yrhB)
SAW: SAHV_0458(yrhB)
SAM: MW0415(metB)
SAS: SAS0418
SAR: SAR0460
SAC: SACOL0503
SAA: SAUSA300_0434(metB)
SAE: NWMN_0425(metB)
SAD: SAAV_0403
SUE: SAOV_0478
SUJ: SAA6159_00410(metB)
SUK: SAA6008_00464(metB)
SUC: ECTR2_394
SUZ: MS7_0434(mccB)
SUG: SAPIG0526
SAUA: SAAG_00915
SAUS: SA40_0399
SAUU: SA957_0414
SAUG: SA268_0412
SAUT: SAI1T1_2003360(yrhB)
SAUJ: SAI2T2_1003360(yrhB)
SAUK: SAI3T3_1003360(yrhB)
SAUQ: SAI4T8_1003360(yrhB)
SAUV: SAI7S6_1003360(metB)
SAUW: SAI5S5_1003350(metB)
SAUX: SAI6T6_1003360(metB)
SAUY: SAI8T7_1003360(metB)
SAUF: X998_0487
SAB: SAB0410
SUY: SA2981_0436(metB)
SAUB: C248_0510
SAUM: BN843_4430
SAUC: CA347_454(mccB)
SAUR: SABB_02175(mccB)
SAUI: AZ30_02230
SAUD: CH52_03550
SAMS: NI36_02155
SEP: SE2323
SER: SERP0095
SEPP: SEB_02318
SEPS: DP17_1515
SHA: SH2548(metB)
SHH: ShL2_02333(metB_2)
SSP: SSP0253
SCA: SCA_0087(metC)
SDT: SPSE_2355(metB2)
SPAS: STP1_1535
SXO: SXYL_00285(metB)
SHU: SHYC_11450(mccB)
SCAP: AYP1020_2183(mccB)
SSCH: LH95_11030
SSCZ: RN70_11795
SAGQ: EP23_10730
MCL: MCCL_1790
MCAK: MCCS_23060(mccB)
ESI: Exig_2343
EAN: Eab7_2188
BBE: BBR47_47850(mccB)
PPY: PPE_02107
PPM: PPSC2_11035(yrhB)
PPO: PPM_2116(yrhB)
PPOL: X809_11380
PPOY: RE92_01315
ASOC: CB4_01041(mccB_2)
JEO: JMA_30770
CRN: CAR_c05790(yrhB)
CAE: SMB_G0947(mccB)
SVE: SVEN_3489
 » show all
Taxonomy
Reference
1  [PMID:14917685]
  Authors
KALLIO RE.
  Title
Function of pyridoxal phosphate in desulfhydrase systems of Proteus morganii.
  Journal
J Biol Chem 192:371-7 (1951)
Other DBs
ExplorEnz - The Enzyme Database: 4.4.1.2
IUBMB Enzyme Nomenclature: 4.4.1.2
ExPASy - ENZYME nomenclature database: 4.4.1.2
BRENDA, the Enzyme Database: 4.4.1.2
CAS: 9024-41-3

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