Task: Text Categorization
Input (English): Transgenic sheep have been engineered to produce this amino acid, necessary for the production of wool. Along with glycine and glutamate, it forms glutathione, a common antioxidant. A variant of it exists containing the element selenium, and its use in dietary supplements raises questions of cannibalism, as a primary source of this amino acid is human hair, where it strengthens the secondary structure of the protein keratin. For 10 points, name this amino acid, whose thiol group when oxidized can bond with another to form a dimer connected by a disulfide bridge.
Output (English): Science