4.2.1.22: cystathionine beta-synthase
This is an abbreviated version!
For detailed information about cystathionine beta-synthase, go to the full flat file.
Word Map on EC 4.2.1.22
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4.2.1.22
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h2s
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sulfide
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homocystinuria
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hyperhomocysteinemia
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artery
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spacer
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corticobasal
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candida
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mthfr
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carotid
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folate
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transsulfuration
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conidia
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cajal
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nahs
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dextrose
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methylenetetrahydrofolate
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bismuth
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hallucinations
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anamorphic
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palsy
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supranuclear
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charles
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remethylation
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reisolated
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conidiophore
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gamma-lyase
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biodiversity
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hyaline
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chemoreceptor
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gasotransmitter
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3-mercaptopyruvate
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frontotemporal
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sulfurtransferase
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thromboembolic
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ascospore
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rinsed
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aminooxyacetic
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apraxia
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snrnps
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symptomless
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hydrosulfide
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marxianus
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visuospatial
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5,10-methylenetetrahydrofolate
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voxel-based
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appressoria
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naocl
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medicine
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diagnostics
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ascus
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phytopathological
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analysis
- 4.2.1.22
- h2s
- sulfide
- homocystinuria
- hyperhomocysteinemia
- artery
-
spacer
-
corticobasal
- candida
- mthfr
-
carotid
- folate
-
transsulfuration
- conidia
-
cajal
- nahs
- dextrose
- methylenetetrahydrofolate
-
bismuth
- hallucinations
-
anamorphic
- palsy
-
supranuclear
-
charles
-
remethylation
-
reisolated
-
conidiophore
-
gamma-lyase
-
biodiversity
-
hyaline
-
chemoreceptor
-
gasotransmitter
- 3-mercaptopyruvate
-
frontotemporal
- sulfurtransferase
-
thromboembolic
- ascospore
-
rinsed
-
aminooxyacetic
- apraxia
-
snrnps
-
symptomless
- hydrosulfide
- marxianus
-
visuospatial
- 5,10-methylenetetrahydrofolate
-
voxel-based
-
appressoria
- naocl
- medicine
- diagnostics
- ascus
-
phytopathological
- analysis
Reaction
Synonyms
Beta-thionase, CBS, CBS424, CDCP2, CNNM2, Cys4, CysB, cystathionine beta synthase, cystathionine beta-synthase, cystathionine beta-synthase domain-containing protein, cystathionine-beta-synthase, Cysteine synthase, EC 4.2.1.21, hCBS, Hemoprotein H-450, LbrM.17.0230, Methylcysteine synthase, osmoprotectant transporter OpuC, PF1953, PH0267, Serine sulfhydrase, Serine sulfhydrylase, Serine sulphhydrase, TA0289, TM0935, TV1335, yCBS, ytCBS
ECTree
4.2.1.22 cystathionine beta-synthaseAdvanced search results
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results (Substrates Products
Substrates Products on EC 4.2.1.22 - cystathionine beta-synthase
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SUBSTRATE 
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
L-serine + H2O
NH3 + pyruvate
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wild-type enzyme shows no beta-elimination reaction, beta elimination is only detectable in the following mutants: T81A, S82A, T85A, Q157A, Q157E, Q157H, Y158F
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?
O-acetyl-L-serine + L-homocysteine
?
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poor substrate for both the wild type and the N- and C-terminally truncated enzyme 71400 CBS
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-
?
2 L-cysteine
(2R,2'R)-3,3'-sulfanediylbis(2-aminopropanoic acid) + H2S
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-
-
?
2 L-cysteine
(2R,2'R)-3,3'-sulfanediylbis(2-aminopropanoic acid) + H2S
Lactiplantibacillus plantarum ATCC BAA-793
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-
-
?
L-Cysteine + 1-mercapto-2-propanol
HOOC-CH(NH2)-CH2-S-CH2-CH(OH)-CH3 + H2S
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-
-
-
?
L-Cysteine + 1-mercapto-2-propanol
HOOC-CH(NH2)-CH2-S-CH2-CH(OH)-CH3 + H2S
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-
-
-
?
L-Cysteine + 1-mercapto-2-propanol
HOOC-CH(NH2)-CH2-S-CH2-CH(OH)-CH3 + H2S
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-
-
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?
L-Cysteine + 1-mercapto-2-propanol
HOOC-CH(NH2)-CH2-S-CH2-CH(OH)-CH3 + H2S
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activated L-serine sulfhydrase
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?
L-Cysteine + 2-mercaptoethanol
HOOC-CH(NH2)-CH2-S-CH2-CH2OH + H2S
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-
-
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?
L-Cysteine + 2-mercaptoethanol
HOOC-CH(NH2)-CH2-S-CH2-CH2OH + H2S
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-
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?
L-Cysteine + 2-mercaptoethanol
HOOC-CH(NH2)-CH2-S-CH2-CH2OH + H2S
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-
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?
L-Cysteine + 2-mercaptoethanol
HOOC-CH(NH2)-CH2-S-CH2-CH2OH + H2S
Steinernema bibionis
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-
-
-
?
L-Cysteine + 2-mercaptoethanol
HOOC-CH(NH2)-CH2-S-CH2-CH2OH + H2S
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-
-
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?
L-cysteine + 2-mercaptoethanol
S-hydroxyethyl-L-cysteine + H2S
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-
?
L-Cysteine + DL-homocysteine
Cystathionine + H2S
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full-length enzyme and truncated enzyme form lacking the C-terminal regulatory domain
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-
?
L-cysteine + L-homocysteine
L-cystathionine + H2S
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-
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?
L-cysteine + L-homocysteine
L-cystathionine + H2S
Lactiplantibacillus plantarum ATCC BAA-793
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-
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?
L-Serine + homocysteine
?
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-
-
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?
L-Serine + homocysteine
?
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reduced activity of EC 4.2.1.22 in patients with homocystinuria due to mutations in the CBS gene
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-
?
L-Serine + homocysteine
?
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initial step in transsulfuration forming cysteine. Homocysteine is a relatively toxic amino acid, which levels have to be kept low
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-
?
L-Serine + homocysteine
Cystathionine + H2O
beta-replacement reaction
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?
L-Serine + homocysteine
Cystathionine + H2O
catalyzes a beta-replacement reaction in which an electronegative substituent in the beta-position of the amino acid substrate is replaced by a nucleophile, binding of L-serine as the external aldimine is faster than formation of the aminoacrylate intermediate, the rate-limiting step is the reaction of aminoacrylate with L-homocysteine to form L-cystathione, rate of the forward reaction is 38fold greater than the reverse reaction
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r
L-Serine + homocysteine
Cystathionine + H2O
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hydroxylgroup of serine is replaced by the thiol of homocysteine
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r
L-Serine + homocysteine
Cystathionine + H2O
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in the forward direction an external aldimine of serine and an aminoacrylate intermediate are formed, the aminoacrylate binds to homocysteine and converts to cystathione, in the reverse reaction cystathione binds to the enzyme and is rapidly converted to the aminoacrylate without accumulation of the external aldimine
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r
L-serine + L-homocysteine
cystathionine + H2O
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-
-
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?
L-serine + L-homocysteine
cystathionine + H2O
the enzyme participates in the process of oocyte maturation
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-
?
L-serine + L-homocysteine
L-cystathionine + H2O
electrostatic stabilization of the zwitterionic carbanion intermediate is afforded by the close positioning of an active site lysine residue that is initially used for Schiff base formation in the internal aldimine and later as a general base, and additional stabilizing interactions between active site residues and the catalytic intermediates
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?
L-serine + L-homocysteine
L-cystathionine + H2O
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696253, 697295, 698182, 698850, 701064, 704664, 714179, 714912, 715808, 715809, 728933, 728945, 730143, 730146, 730755
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?
O-acetyl-L-serine + H2O
pyruvate + acetate + NH3
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-
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?
O-acetyl-L-serine + L-homocysteine
cystathionine + acetate
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-
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?
O-acetyl-L-serine + L-homocysteine
cystathionine + acetate
Lactiplantibacillus plantarum ATCC BAA-793
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-
-
?
additional information
?
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O-acetylserine sulfhydrylase isozyme A, OASSAp, EC 2.5.1.65, exhibits both O-acetylserine sulfhydrylase and cystathionine beta-synthase activities
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-
?
additional information
?
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key enzyme involved in intracellular metabolism of homocysteine
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?
additional information
?
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elevated total plasma homocysteine is an independent risk factor in the development of vascular disease in humans. Elevating cystathionine beta-synthase level is an effective method to lower plasma homocysteine levels
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-
?
additional information
?
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the enzyme may have additional in vivo functions beyond its role as a homocysteine metabolizing enzyme
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?
additional information
?
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the overexpression of cystathionine beta-synthase may cause the developmental abnormality in cognition in Down's syndrome children and may lead to Alzheimer type of disease in Down's syndrom adults
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-
?
additional information
?
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the cystathionine beta-synthase variant c.844_845ins68 protects against CNS demyelination in X-linked adrenoleukodystrophy
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-
?
additional information
?
-
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the oxidation of CBS by dioxygen appears to proceed directly from the ferrous to the ferric state, presumably via an outer sphere electron transfer reaction
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-
?
additional information
?
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the enzyme performs L-cysteine sythesis from L-serine
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-
?
additional information
?
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the enzyme performs L-cysteine sythesis from L-serine
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-
?
additional information
?
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cysteine is able to partially compete with serine on CBS, thus leading to generation of appreciable amounts of H2S. The leading H2S-producing reaction is condensation of cysteine with homocysteine, while cysteine desulfuration plays a dominant role when cysteine is more abundant than serine and homocysteine is limited. The serine-to-cysteine ratio is the main determinant of CBS H2S productivity. Abundance of cysteine over serine, for example, in blood plasma, allows for up to 43% of CBS activity being responsible for H2S production, while excess of serine typical for intracellular levels effectively limited such activity to less than 1.5%. CBS also produces lanthionine from serine and cysteine
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-
?
additional information
?
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cystathionine beta-synthase is a key enzyme for homocysteine metabolism, it is associated with the generation and/or differentiation of the radial glia/astrocyte linage cells in the developing central nervous system
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-
?
additional information
?
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hyperhomocysteinaemia is a metabolic disorder associated with the development of premature atherosclerosis. Cystathionine beta-synthase activity is significantly decreased in mice with a plasma homocysteine value greater than 0.015 mg
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?
additional information
?
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role for CBS as a mediator in interactions between oocyte and granulosa cells
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?
additional information
?
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cystathionine-beta-synthase domains in the ATP-binding component of OpuC are required for transporter function
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?
additional information
?
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plasma albumin cysteinylation is regulated by cystathionine beta-synthase
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?
additional information
?
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CBS also catalyze H2S production in vitro
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?
additional information
?
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no substrates: D-, L-allo- and D-allo-cystathionine
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?
additional information
?
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cystathionine beta-synthase also catalyze H2S production. The most efficient route for H2S generation by cystathionine beta-synthase is the beta-replacement of the cysteine thiol with homocysteine. In this reaction, cystathionine beta-synthase first reacts with cysteine to release H2S and forms an aminoacrylate intermediate. Homocysteine binds to the E 3 aminoacrylate intermediate with a bimolecular rate constant of 142 mM/s and rapidly condenses to form the enzyme-bound external aldimine of cystathionine. The reactions could be partially rate limited by release of the products, cystathionine and H2S
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-
?
additional information
?
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key enzyme in the trans-sulfuration pathway. Cystathionine beta-synthase may be an oxidative defense enzyme in the eye tissue, in particular in the segments of the eye where constant environmental oxidative stress is imposed
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-
?
