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.
Human cysteine metabolism
[edit]In human cysteine metabolism,[citation needed] L-cysteine is consumed in several ways as shown below. L-Cysteine is also consumed in pantothenate/coenzyme A biosynthesis.
| Enzyme | → | Products | Cofactor/Additional Reactant |
|---|---|---|---|
| cysteine dioxygenase[1] | → | cysteine sulfinic acid | iron |
| serine racemase[2] | → | D-cysteine | pyridoxal phosphate |
| cysteine lyase[3] | → | L-cysteate/hydrogen sulfide | pyridoxal phosphate/sulfite |
| cystathionine γ-lyase[4] | → | pyruvate/NH3/H2S | pyridoxal phosphate |
| cysteine—tRNA ligase[5] | → | L-cysteinyl-tRNACys | |
| cystine reductase[6] | → | L-cystine/NADH and H+ | NAD+ |
| cysteine transaminase[7] | → | 3-mercapto-pyruvate/L-glutamate | pyridoxal phosphate/alpha-ketoglutaric acid |
| glutamate–cysteine ligase[8] | → | γ-glutamyl cysteine/ADP and Pi | ATP |
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.
| Reactants | → | Enzyme | Cofactors | Notes |
|---|---|---|---|---|
| O-acetyl-L-serine/hydrogen sulfide | → | cysteine synthase[9] | pyridoxal phosphate | not present in humans |
| L-cystine/2 glutathione | → | glutathione-cystine transhydrogenase[10] | ||
| cystathionine | → | cystathionine γ-lyase[4] | pyridoxal phosphate | |
| 3-mercapto-pyruvate | → | cysteine transaminase[7] | pyridoxal phosphate |
References
[edit]- ^ Stipanuk MH, Ueki I, Dominy JE, Simmons CR, Hirschberger LL (May 2009). "Cysteine dioxygenase: a robust system for regulation of cellular cysteine levels". Amino Acids. 37 (1): 55–63. doi:10.1007/s00726-008-0202-y. PMC 2736881. PMID 19011731.
- ^ Roychaudhuri R (March 2023). "Mammalian D-Cysteine: A new addition to the growing family of biologically relevant D-amino acids". Chirality: chir.23555. doi:10.1002/chir.23555. PMID 36890664. S2CID 257426578.
- ^ Tolosa EA, Chepurnova NK, Khomutov RM, Severin ES (February 1969). "Reactions catalysed by cysteine lyase from the yolk sac of chicken embryo". Biochimica et Biophysica Acta (BBA) - Enzymology. 171 (2): 369–371. doi:10.1016/0005-2744(69)90174-0. PMID 5813025.
- ^ a b Sun Q, Collins R, Huang S, Holmberg-Schiavone L, Anand GS, Tan CH, et al. (January 2009). "Structural basis for the inhibition mechanism of human cystathionine gamma-lyase, an enzyme responsible for the production of H(2)S". The Journal of Biological Chemistry. 284 (5): 3076–3085. doi:10.1074/jbc.M805459200. PMID 19019829.
- ^ Mccorquodale DJ (December 1964). "The separation and partial purification of aminoacyl-RNA synthetases from Escherichia coli". Biochimica et Biophysica Acta (BBA) - Specialized Section on Nucleic Acids and Related Subjects. 91 (4): 541–548. doi:10.1016/0926-6550(64)90001-5. PMID 14262440.
- ^ Maresca B, Jacobson E, Medoff G, Kobayashi G (September 1978). "Cystine reductase in the dimorphic fungus Histoplasma capsulatum". Journal of Bacteriology. 135 (3): 987–992. doi:10.1128/jb.135.3.987-992.1978. PMC 222474. PMID 211119.
- ^ a b Hipólito A, Nunes SC, Vicente JB, Serpa J (September 2020). "Cysteine Aminotransferase (CAT): A Pivotal Sponsor in Metabolic Remodeling and an Ally of 3-Mercaptopyruvate Sulfurtransferase (MST) in Cancer". Molecules. 25 (17): 3984. doi:10.3390/molecules25173984. PMC 7504796. PMID 32882966.
- ^ Chen Y, Shertzer HG, Schneider SN, Nebert DW, Dalton TP (October 2005). "Glutamate cysteine ligase catalysis: dependence on ATP and modifier subunit for regulation of tissue glutathione levels". The Journal of Biological Chemistry. 280 (40): 33766–33774. doi:10.1074/jbc.M504604200. PMID 16081425.
- ^ Kredich NM, Becker MA, Tomkins GM (May 1969). "Purification and characterization of cysteine synthetase, a bifunctional protein complex, from Salmonella typhimurium". The Journal of Biological Chemistry. 244 (9): 2428–2439. doi:10.1016/S0021-9258(19)78241-6. PMID 4977445.
- ^ Nagai S, Black S (April 1968). "A thiol-disulfide transhydrogenase from yeast". The Journal of Biological Chemistry. 243 (8): 1942–1947. doi:10.1016/S0021-9258(18)93532-5. PMID 5646485.