1. A nonessential amino acid containing sulfur that is found in proteins and plays a role in protein structure and enzyme function.
Usage: biochemistry; often used in scientific and medical contexts

Examples

• Cysteine is one of the 20 standard amino acids used by cells to synthesize proteins.
• The sulfur atom in cysteine allows it to form disulfide bonds with other cysteine residues.
• Cysteine can be synthesized by the body from the amino acid methionine.
• Hair and nails contain high levels of cysteine due to its role in keratin formation.
• Researchers studied how cysteine mutations affect protein folding in the disease model.