an amino acid containing sulfur that is found in most proteins; oxidizes on exposure to air to form cystine
"The biochemist noted that when cysteine was left open to the laboratory fumes, it slowly oxidized into cystine."
A sulphur-containing nonessential amino acid C₃H₇NO₂S found in most animal proteins; it readily oxidizes to cystine.
"The biochemistry professor explained that adding extra cysteine helps stabilize the structure of certain enzymes before they are subjected to high-temperature cooking."