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Information on EC 4.2.1.22 - cystathionine beta-synthase and Organism(s) Homo sapiens and UniProt Accession P35520

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     4 Lyases
         4.2 Carbon-oxygen lyases
             4.2.1 Hydro-lyases
                4.2.1.22 cystathionine beta-synthase
IUBMB Comments
A pyridoxal-phosphate protein. A multifunctional enzyme: catalyses beta-replacement reactions between L-serine, L-cysteine, cysteine thioethers, or some other beta-substituted alpha-L-amino acids, and a variety of mercaptans.
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This record set is specific for:
Homo sapiens
UNIPROT: P35520
Word Map
The expected taxonomic range for this enzyme is: Archaea, Eukaryota, Bacteria
The taxonomic range for the selected organisms is: Homo sapiens
Synonyms
Beta-thionase, CBS, CBS424, CDCP2, CNNM2, Cys4, CysB, cystathionine beta synthase, cystathionine beta-synthase, cystathionine beta-synthase domain-containing protein, more
SYNONYM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Beta-thionase
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CBS424
247
inactive form of CBS
cystathionine-beta-synthase
247
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Cysteine synthase
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hCBS
247
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Hemoprotein H-450
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Methylcysteine synthase
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Serine sulfhydrase
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Serine sulfhydrylase
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Serine sulphhydrase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
L-serine + L-homocysteine = L-cystathionine + H2O
show the reaction diagram
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
C-S bond formation
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elimination
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SYSTEMATIC NAME
IUBMB Comments
L-serine hydro-lyase (adding homocysteine; L-cystathionine-forming)
A pyridoxal-phosphate protein. A multifunctional enzyme: catalyses beta-replacement reactions between L-serine, L-cysteine, cysteine thioethers, or some other beta-substituted alpha-L-amino acids, and a variety of mercaptans.
CAS REGISTRY NUMBER
COMMENTARY hide
9023-99-8
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SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
L-cysteine
H2S + L-serine
show the reaction diagram
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?
L-cysteine + L-homocysteine
L-cystathionine + H2S
show the reaction diagram
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?
L-cysteine + L-serine
lanthionine + H2O
show the reaction diagram
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?
L-serine + H2S
L-cysteine
show the reaction diagram
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?
L-serine + L-homocysteine
L-cystathionine + H2O
show the reaction diagram
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?
L-cysteine + 2-mercaptoethanol
S-hydroxyethyl-L-cysteine + H2S
show the reaction diagram
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?
L-Cysteine + DL-homocysteine
Cystathionine + H2S
show the reaction diagram
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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
show the reaction diagram
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r
L-serine + cysteamine
L-thialysine
show the reaction diagram
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?
L-Serine + homocysteine
?
show the reaction diagram
L-Serine + homocysteine
Cystathionine + H2O
show the reaction diagram
L-Serine + HS-
Cysteine + OH-
show the reaction diagram
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L-serine + L-cysteine
?
show the reaction diagram
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?
L-serine + L-homocysteine
cystathionine + H2O
show the reaction diagram
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?
L-serine + L-homocysteine
L-cystathionine + H2O
show the reaction diagram
O-acetyl-L-serine + L-homocysteine
?
show the reaction diagram
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poor substrate for both the wild type and the N- and C-terminally truncated enzyme 71–400 CBS
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?
additional information
?
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
L-serine + L-homocysteine
L-cystathionine + H2O
show the reaction diagram
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?
L-Serine + homocysteine
?
show the reaction diagram
L-serine + L-homocysteine
cystathionine + H2O
show the reaction diagram
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?
L-serine + L-homocysteine
L-cystathionine + H2O
show the reaction diagram
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?
additional information
?
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
pyridoxal 5'-phosphate
pyridoxal 5'-phosphate
S-adenosyl-L-methionine
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Co2+
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97.1% Fe2+ and 2.9% Co2+ in wild-type FeCBS enzyme, 8% Fe2+ and 92% Co2+ in the CoCBS enzyme variant
Co3+
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cobalt-substituted variant of hCBS, i.e. Co hCBS, in which CoPPIX replaces FePPIX, i.e. heme. Co(III) hCBS is a unique Co-substituted heme protein: the Co(III) ion is 6-coordinate, low-spin, diamagnetic, and bears a cysteine(thiolate) as one of its axial ligands. Electronic absorption and MCD spectra of the Co-substituted heme protein, overview. Co(III) hCBS is slowly reduced to Co(II) hCBS, which contains a 5-coordinate, low-spin, S = 1/2 Co-porphyrin that does not retain the cysteine(thiolate) ligand. This form of Co(II)hCBS binds NO but not CO. Co(II) hCBS is reoxidized in the air to form a new Co(III) form, which does not contain a cysteine(thiolate) ligand. Maintaining the native heme ligation motif of wild-type Fe hCBS (Cys/His) is essential in maintaining maximal activity in Co hCBS
Fe3+
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additional information
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
L-homocysteine
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(5Z)-5-[(4-hydroxy-3-methoxyphenyl)methylidene]-3-methyl-2-(methylsulfanyl)-3,5-dihydro-4H-imidazol-4-one
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compound derived from polyandrocarpamines A and B, i.e. 2-aminoimidazolone compounds isolated from the ascidian Polyandrocarpa sp.
2-methoxy-4-[(Z)-(5-oxo-2-sulfanylideneimidazolidin-4-ylidene)methyl]phenyl acetate
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compound derived from polyandrocarpamines A and B, i.e. 2-aminoimidazolone compounds isolated from the ascidian Polyandrocarpa sp.
Amino-oxyacetate
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complete inhibition at 0.05 mM
aminooxyacetic acid
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carbon monoxide
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Co3+
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Co3+ has 30-60% of the specific activity of Fe3+-CBS
cyanide
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Hg2+
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reactivity of Co(III) hCBS with HgCl2 is consistent with a loss of the cysteine(thiolate) ligand. 2-Mercaptoethanol is unable to reverse the Hg-induced ligand switch, in contrast to some other heme-thiolate proteins
HgCl2
hydroxylamine
L-homocysteine
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substrate inhibition
Mn3+
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Mn3+ has 30-60% of the specific activity of Fe3+-CBS
nitric oxide
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peroxynitrite
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exposure to peroxynitrite does not modify bound pyridoxal 5'-phosphate but leads to nitration of Trp208, Trp43 and Tyr223 and alterations in the heme environment including loss of thiolate coordination, conversion to high-spin and bleaching, with no detectable formation of oxoferryl compounds nor promotion of one-electron processes
regulatory domain
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exerts an inhibitory effect on the enzyme, deletion is correlated with a 1fold increase in catalytic activity
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additional information
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
S-adenosyl-L-methionine
AdoMet
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allosteric regulator, 1mol per mole of monomeric subunit activates the enzyme 2fold
betaine
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activates, effects on wild-type and mutant enzymes, overview
delta-aminolevulinic acid
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activates, effects on wild-type and mutant enzymes, overview
glycerol
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activates, effects on wild-type and mutant enzymes, overview
heme
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regulatory role
pyridoxal 5'-phosphate
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S-adenosyl-L-methionine
S-adenosylhomocysteine
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stimulates activity 1.1fold at 0.48 mM
sinefungin
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stimulates activity 1.28fold at 1 mM
tumor necrosis factor-alpha
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leads to cleavage of the enzyme to a truncated form and therefore increases the activity, 50% increase of activity after treatment of HepG2 cells for 16 h
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additional information
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