This image is a scaled-down version of the actual pathway image. It does not contain any links to the protein information pages.
|
|
Description |
Cysteine is not an essential amino acid, but it arises in mammals from
methionine, which is essential, and serine, which is not. In the absence of
dietary methionine, animals cannot make cysteine. Mammals require homocysteine
(from the degradation of Methionine) as source of sulfur and produce cysteine.
Homocysteine reacts with serine in a reaction catalyzed by CBS
(Cystathionine Beta-Synthase) to yield Cystathionine. CTH
(Cystathionine Gamma-lyase), a pyridoxal phosphate enzyme, catalyzes the
cleavage of Cystathionine to yield free cysteine, with Alpha-ketobutyrate and
NH3 as the products. Cysteine is an allosteric inhibitor of Cystathionine
Gamma-lyase (Ref.1). While the sulfur in Cysteine comes from homocysteine, the
rest of the molecule comes from the initial serine residue.
Cysteine is
an important amino acid for all [...] |
|
|
References:
|
|
|
|
|