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4.2.1.22 |
Description |
Cystathionine beta-synthase |
Alternative names |
Serine sulfhydrase; Beta-thionase; Methylcysteine synthase. |
Catalyzed reaction |
L-serine + L-homocysteine = cystathionine + H(2)O. |
Cofactor |
Pyridoxal-phosphate. |
Comments |
-!- A multifunctional enzyme: catalyzes beta-replacement reaction between L-serine, L-cysteine, cysteine thioethers or some other beta- substituted alpha-L-amino acids and a variety of mercaptans. -!- Formerly EC 4.2.1.21. |
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This is the first enzyme in the transsulfuration pathway, catalyzing the formation of cystathionine. Besides its canonical reaction, cystathionine beta-synthase can catalyze alternative reactions that produce hydrogen sulfide, a neuromodulator.
Mammalian cystathionine beta-synthases, but not the yeast enzyme, also bind a heme molecule, and the heme-binding domain is believed to regulate the enzyme in response to redox conditions.
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Diseases |
Homocystinuria I (classic form); Homocysteinemia. |
Prosite |
PROSITE; PDOC00700; |
PDB |
1JBQ; 1M54; 4L0D; 5OHX; |
Organisms |
-Eubacteria -Fungi -Metazoa -Human |
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Family |
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Links |
Enzyme (activities) 4.2.1.22
BRENDA (activities) 4.2.1.22
KEGG (pathways) 4.2.1.22
PLPMDB (PLP mutants) 4.2.1.22
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References |
Chang Z, Vining LC (2002) Biosynthesis of sulfur-containing amino acids in Streptomyces venezuelae ISP5230: roles for cystathionine beta-synthase and transsulfuration Microbiology 148 2135-2147. Li, D. Y.; Ji, X. S.; Yu, J.; Chen, M. J.; Yuan, Z. Y. (2001) PCR Based Cloning and Sequence Analysis of the Pichia pastoris Cystathionine beta-Synthase Gene Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao 33 600-606. Nozaki, T.; Shigeta, Y.; Saito-Nakano, Y.; Imada, M.; Kruger, W.D. (2001) Characterization of transsulfuration and cysteine biosynthetic pathways in the protozoan hemoflagellate, Trypanosoma cruzi. Isolation and molecular characterization of cystathionine beta-synthase and serine acetyltransferase from Trypanosoma J Biol Chem 276 6516-23. Jhee, K. H.; McPhie, P.; Miles, E. W. (2000) Yeast cystathionine beta-synthase is a pyridoxal phosphate enzyme but, unlike the human enzyme, is not a heme protein J Biol Chem 275 11541-4. Bukovska, G.; Kery, V.; Kraus, J. P. (1994) Expression of human cystathionine beta-synthase in Escherichia coli: purification and characterization Protein Expr Purif 5 442-8. Articles on 4.2.1.22 |
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last changed |
2019/06/21 13:16 |
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