cystine

/ˈsɪstiːn/
noun
  1. An amino acid found in proteins, especially in hair, skin, and nails, that helps form strong bonds in protein structures.
    • Some people have a condition where cystine builds up in the kidneys.
    • Cystine is important for the structure of keratin in hair and nails.
    • The body uses cystine to build and repair tissues.
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