Cysteine Metabolism - Human Cysteine Metabolism

Human Cysteine Metabolism

In human cysteine metabolism, L-cysteine is consumed in several ways as shown below. L-cysteine is also consumed in methionine and glutathione metabolism as well as pantothenate/CoA biosynthesis.

L-cysteine consumption pathways
Enzyme Product
cysteine dioxygenase 3-sulfino-L-alanine (or cysteine sulfinic acid)
amino-acid racemase D-cysteine
cysteine lyase L-cysteate
cysteine—tRNA ligase L-cysteinyl-tRNACys
cystine reductase L-cystine
cysteine transaminase 3-mercapto-pyruvate

L-cysteine is the product of several processes as well. In addition to the reactions below, L-cysteine is also a product of glycine, serine, and threonine metabolism.

L-cysteine production pathways
Starting chemical Enzyme
O-acetyl-L-serine cysteine synthase
L-cystine glutathione-cystine transhydrogenase
pyruvate cystathionine γ-lyase
3-mercapto-pyruvate cysteine transaminase

Read more about this topic:  Cysteine Metabolism

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