cysteine

noun

cys·​te·​ine ˈsi-stə-ˌēn 

: a crystalline sulfur-containing amino acid C₃H₇NO₂S readily oxidizable to cystine

Examples of cysteine in a Sentence

Recent Examples on the Web

So the scientists exposed the tardigrades to different kinds of molecules known to block cysteine oxidation, as scientists call binding by a free radical. —Meghan Bartels, Scientific American, 17 Jan. 2024

The survival mechanism kicks off when cysteines, one of the amino acids that forms proteins in the body, come into contact with these oxygen free radicals and becomes oxidized, the researchers found. —Jenna Schnuer, CNN, 5 Feb. 2024

The team noticed that, in particular, the free radicals reacted with cysteine, an amino acid used in protein production. —Christian Thorsberg, Smithsonian Magazine, 18 Jan. 2024

Under stressful conditions, with cysteine unavailable to the free radicals being produced, the tardigrades couldn’t form tuns. —Meghan Bartels, Scientific American, 17 Jan. 2024

Word History

Etymology

International Scientific Vocabulary, from cystine + -ein

First Known Use

1884, in the meaning defined above

Medical Definition

cysteine

noun

cys·​teine ˈsis-tə-ˌēn 

: a sulfur-containing amino acid C₃H₇NO₂S occurring in many proteins and glutathione and readily oxidizable to cystine

—abbreviation Cys