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B6db activities: 4.2.1.22

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.
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.
Diseases Homocystinuria I (classic form); Homocysteinemia.
Prosite PROSITE; PDOC00700;
PDB 1JBQ; 1M54; 4L0D;
Organisms -Bacteria -Fungi -Metazoa -Human
 

Family 

4.2.1.22 (23)
 
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
 
References Articles on 4.2.1.22
 
last changed 2014/03/20 11:15

B6db activities