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Literature summary for 4.2.1.22 extracted from

  • Miles, E.W.; Kraus, J.P.
    Cystathionine {beta}-synthase: structure, function, regulation and location of homocystinuria-causing mutations (2004), J. Biol. Chem., 279, 29871-29874.
    View publication on PubMed
Search for more literature for 4.2.1.22

Activating Compound

Activating Compound Comment Organism Structure
additional information enzyme can not be activated by S-adenosyl-L-methionine Trypanosoma cruzi
S-adenosyl-L-methionine 3fold activation, allosteric regulator Saccharomyces cerevisiae
S-adenosyl-L-methionine 3fold activation, allosteric regulator of the full length enzyme, does not activate the truncated enzyme Homo sapiens

Application

Application Comment Organism
medicine inherited dysfunction of the enzyme leads to homocystinurea, mutations can occur at the dimer interface, the active site, the heme-binding site and the predicted interface region between the catalytic domain and the missing regulatory domain of the truncated enzyme Homo sapiens

Protein Variants

Protein Variants Comment Organism
S466L enzyme is constitutively activated, does bind S-adenosyl-L-methionine, but is not activated by it Homo sapiens

Organism

Organism UniProt Comment Textmining
Homo sapiens P35520
-
-
Saccharomyces cerevisiae
-
-
-
Trypanosoma cruzi
-
-
-

Reaction

Reaction Comment Organism Reaction ID
L-serine + L-homocysteine = L-cystathionine + H2O ping-pong mechanism Saccharomyces cerevisiae
a
L-serine + L-homocysteine = L-cystathionine + H2O ping-pong mechanism Homo sapiens
a

Source Tissue

Source Tissue Comment Organism Textmining
fibroblast
-
 Homo sapiens
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
L-cysteine + 2-mercaptoethanol
-
 Homo sapiens S-hydroxyethyl-L-cysteine + H2S
-
 ?
L-Serine + homocysteine
-
 Saccharomyces cerevisiae Cystathionine + H2O
-
 r
L-Serine + homocysteine
-
 Trypanosoma cruzi Cystathionine + H2O
-
 r
L-Serine + homocysteine 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 Homo sapiens Cystathionine + H2O
-
 r

Cofactor

Cofactor Comment Organism Structure
heme
-
 Homo sapiens
additional information heme is no cofactor Saccharomyces cerevisiae
additional information heme is no cofactor Trypanosoma cruzi
pyridoxal 5'-phosphate
-
 Saccharomyces cerevisiae
pyridoxal 5'-phosphate
-
 Trypanosoma cruzi
pyridoxal 5'-phosphate dependent Homo sapiens