Cysteine metabolism

Cysteine metabolism refers to the biological pathways that consume or create cysteine. The pathways of different amino acids and other metabolites interweave and overlap to creating complex systems.cysteine is metabolism creating complex systems

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/coenzyme A biosynthesis.

L-Cysteine consumption pathways
EnzymeCofactor/Additional ReactantProducts
cysteine dioxygenaseironcysteine sulfinic acid
amino-acid racemasepyridoxal phosphateD-cysteine
cysteine lyasepyridoxal phosphate/sulfiteL-cysteate/hydrogen sulfide
cystathionine γ-lyasepyridoxal phosphateNH3/H2S
cysteine—tRNA ligaseL-cysteinyl-tRNACys
cystine reductaseNAD+L-cystine/NADH and H+
cysteine transaminasepyridoxal phosphate/alpha-ketoglutaric acid3-mercapto-pyruvate/L-glutamate

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
ReactantsEnzymeCofactors
O-acetyl-L-serine/hydrogen sulfidecysteine synthasePyridoxal phosphate
L-cystine/2 glutathioneglutathione-cystine transhydrogenase
cystathioninecystathionine γ-lyasepyridoxal phosphate
3-mercapto-pyruvatecysteine transaminasepyridoxal phosphate

See also

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