Biology:Cysteine metabolism

From HandWiki

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,[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 → 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.

L-cysteine production pathways
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

  1. ↑ "Cysteine dioxygenase: a robust system for regulation of cellular cysteine levels". Amino Acids 37 (1): 55–63. May 2009. doi:10.1007/s00726-008-0202-y. PMID 19011731. 
  2. ↑ "Mammalian D-Cysteine: A new addition to the growing family of biologically relevant D-amino acids". Chirality: chir.23555. March 2023. doi:10.1002/chir.23555. PMID 36890664. 
  3. ↑ "Reactions catalysed by cysteine lyase from the yolk sac of chicken embryo". Biochimica et Biophysica Acta (BBA) - Enzymology 171 (2): 369–371. February 1969. doi:10.1016/0005-2744(69)90174-0. PMID 5813025. 
  4. ↑ 4.0 4.1 "Structural basis for the inhibition mechanism of human cystathionine gamma-lyase, an enzyme responsible for the production of H(2)S" (in English). The Journal of Biological Chemistry 284 (5): 3076–3085. January 2009. doi:10.1074/jbc.M805459200. PMID 19019829. 
  5. ↑ "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. December 1964. doi:10.1016/0926-6550(64)90001-5. PMID 14262440. 
  6. ↑ "Cystine reductase in the dimorphic fungus Histoplasma capsulatum". Journal of Bacteriology 135 (3): 987–992. September 1978. doi:10.1128/jb.135.3.987-992.1978. PMID 211119. 
  7. ↑ 7.0 7.1 "Cysteine Aminotransferase (CAT): A Pivotal Sponsor in Metabolic Remodeling and an Ally of 3-Mercaptopyruvate Sulfurtransferase (MST) in Cancer". Molecules 25 (17): 3984. September 2020. doi:10.3390/molecules25173984. PMID 32882966. 
  8. ↑ "Glutamate cysteine ligase catalysis: dependence on ATP and modifier subunit for regulation of tissue glutathione levels" (in English). The Journal of Biological Chemistry 280 (40): 33766–33774. October 2005. doi:10.1074/jbc.M504604200. PMID 16081425. 
  9. ↑ "Purification and characterization of cysteine synthetase, a bifunctional protein complex, from Salmonella typhimurium". The Journal of Biological Chemistry 244 (9): 2428–2439. May 1969. doi:10.1016/S0021-9258(19)78241-6. PMID 4977445. 
  10. ↑ "A thiol-disulfide transhydrogenase from yeast". The Journal of Biological Chemistry 243 (8): 1942–1947. April 1968. doi:10.1016/S0021-9258(18)93532-5. PMID 5646485. 

See also



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