[sis-teen, -tin] 
| a crystalline amino acid, C6H12O4N2S2, occurring in most proteins, esp. the keratins in hair, wool, and horn, and yielding cysteine on reduction. |
| cys·tine (sĭs'tēn') n. A white crystalline amino acid, C6H12N2O4S2, formed from the disulfide linkage of two cysteines during folding of many proteins, especially keratin, and stabilizing the tertiary structure of the protein. [From its discovery in bladder stones.] |
cystine cys·tine (sĭs'tēn')
n.
A white crystalline amino acid that is found in many proteins, especially keratin, and is the major source of metabolic sulfur.
cystine
a crystalline, sulfur-containing amino acid that is formed from two molecules of the amino acid cysteine. Cystine can be converted to cysteine by reduction (in this case, the addition of hydrogen). Discovered in 1810, cystine was not recognized as a component of proteins until 1899, when it was isolated from animal horn. Cystine is particularly abundant in skeletal and connective tissues and in hair, horn, and wool.
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tin