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Last Updated: 2019-08-16
Homocysteine is an amino acid and homologue of cysteine that appears in the body as a result of the degradation of methionine. In mammals, homocysteine is used to biosynthesize cysteine via the following pathway. First the enzyme cystathionine beta-synthetase irreversibly condenses homocysteine with L-serine, forming L-cystathionine. The L-cystathionine is then cleaved by cystathionine gamma-lyase, producing 2-oxobutanoate, L-cysteine, and ammonia. The 2-oxobutanoate is further broken down via the 2-oxobutanoate degradation pathway, producing citric acid cycle intermediates, while the L-cysteine goes to the cysteine metabolism pathway. The homocysteine degradation pathway composes a part of the larger methionine metabolism pathway.
Homocysteine Degradation References
Genome sequence of the nematode C. elegans: a platform for investigating biology. Science. 1998 Dec 11;282(5396):2012-8. doi: 10.1126/science.282.5396.2012.Pubmed: 9851916
Budde MW, Roth MB: The response of Caenorhabditis elegans to hydrogen sulfide and hydrogen cyanide. Genetics. 2011 Oct;189(2):521-32. doi: 10.1534/genetics.111.129841. Epub 2011 Aug 11.Pubmed: 21840852
Ma DK, Vozdek R, Bhatla N, Horvitz HR: CYSL-1 interacts with the O2-sensing hydroxylase EGL-9 to promote H2S-modulated hypoxia-induced behavioral plasticity in C. elegans. Neuron. 2012 Mar 8;73(5):925-40. doi: 10.1016/j.neuron.2011.12.037.Pubmed: 22405203
This pathway was propagated using PathWhiz - Pon, A. et al. Pathways with PathWhiz (2015) Nucleic Acids Res. 43(Web Server issue): W552–W559.
Propagated from SMP0000455
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