Amino-3-mercaptopropionic acid; the l-isomer is found in most proteins; especially abundant in keratin.
- c. desulfhydrase SYN: cystathionine γ-lyase.
- c. synthase SYN: cystathionine β-synthase.
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cys·teine 'sis-tə-.ēn n a sulfur-containing amino acid C3H7NO2S occurring in many proteins and glutathione and readily oxidizable to cystine abbr. Cys
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n.
a sulphur-containing amino acid that is an important constituent of many enzymes. The disulphide (S-S) links between adjacent cysteine molecules in polypeptide chains contribute to the three-dimensional molecular structure of proteins.
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cys·te·ine (sisґte-ēn) chemical name: 2-amino-3-mercaptopropanoic acid. A sulfur-containing nonessential amino acid produced by the enzymatic or acid hydrolysis of proteins. It is easily oxidized to cystine, is sometimes found in the urine, and has limited detoxification properties. Symbols Cys and C. See also table at amino acid.Medical dictionary. 2011.