cysteine Biochem.
(ˈsɪstiːɪn, ˈsɪstiːaɪn)
Also -ein.
[ad. G. cysteïn (E. Baumann 1882, in Zeitschr. f. physiol. Chem. VIII. 302), f. cystine + -eine.]
An amino-acid, HS·CH2·CH(NH2)·COOH, which is a reduction product of cystine and a constituent of glutathione and many proteins.
| 1884 Jrnl. Chem. Soc. XLVI. A. 1382 Cystine and Cysteïne... The hydrochloride of the new base cysteïne is obtained by evaporating the filtrate. 1923 Nature 24 Feb. 274/1 The reduction of methylene blue by the sulphydryl compounds, reduced glutathione, cystein, and thioglycollic acid, is an autocatalytic reaction. 1961 Lancet 8 July 87/2 Two cysteine molecules readily give up their hydrogen atoms..to reunite as cystine. 1970 R. W. McGilvery Biochem. xvii. 382 Cystine enters metabolism as cysteine. |