Cysteine metabolism

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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.

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Human cysteine metabolism

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.

L-Cysteine consumption pathways
Enzyme→ProductsCofactor/Additional Reactant
cysteine dioxygenase [1] → cysteine sulfinic acid iron
serine racemase [2] →D-cysteinepyridoxal phosphate
cysteine lyase [3] → L-cysteate/hydrogen sulfidepyridoxal phosphate/sulfite
cystathionine γ-lyase [4] →pyruvate/NH3/H2Spyridoxal phosphate
cysteine—tRNA ligase [5] →L-cysteinyl-tRNACys
cystine reductase [6] →L-cystine/NADH and H+NAD+
cysteine transaminase [7] → 3-mercapto-pyruvate/L-glutamatepyridoxal phosphate/alpha-ketoglutaric acid
glutamate–cysteine ligase [8] →γ-glutamyl cysteine/ADP and PiATP

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
Reactants→EnzymeCofactorsNotes
O-acetyl-L-serine/hydrogen sulfide→ cysteine synthase [9] pyridoxal phosphatenot 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

  1. ↑ 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.
  2. ↑ 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.
  3. ↑ 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.
  4. 1 2 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.
  5. ↑ 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.
  6. ↑ 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.
  7. 1 2 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.
  8. ↑ 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.
  9. ↑ 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.
  10. ↑ 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.

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