Cysteine metabolism 4629182 214671381 2008-05-24T18:33:56Z Neuron1 7127559 improved readability of first setnence {{Cleanup|date=September 2006}} '''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. ==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. {| class="wikitable" style="text-align:center" |+ '''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-tRNA<sup>Cys</sup> |- | [[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. {| class="wikitable" style="text-align:center" |+ '''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]] |} ==See also== * [[D-cysteine desulfhydrase]] [[Category:Sulfur metabolism]] [[Category:Sulfur amino acids]]