cysteine

== English == === Etymology === An alteration of cystine, see -eine. === Pronunciation === (Received Pronunciation) IPA(key): /ˈsɪs.təˌiːn/, /ˈsɪs.tə.ɪn/, /ˈsɪs.tiˌiːn/, /ˈsɪs.ti.ɪn/ (General American) IPA(key): /ˈsɪs.təˌin/, /ˈsɪs.tə.ɪn/, /ˈsɪs.tiˌin/, /ˈsɪs.ti.ɪn/, /ˈsɪˌstin/ Rhymes: -ɪstin Hyphenation: cys‧te‧ine === Noun === cysteine (countable and uncountable, plural cysteines) (biochemistry) A sulphur-containing nonessential amino acid C3H7NO2S found in most animal proteins; it readily oxidizes to cystine. ==== Usage notes ==== When used as the name of a substance, this noun is uncountable, but when used as the name of individual molecules, it is countable. ==== Synonyms ==== E910 when used as a food additive E920 when used as an improving agent Cys when viewed as a monomer in proteins ==== Derived terms ==== ==== Related terms ==== homocysteine ==== Translations ==== === References ===