A sulphur-containing amino acid which occurs in keratins and other proteins, often in the form of cystine, and is a constituent of many enzymes.
Chemical formula: HSCH₂CH(NH₂)COOH‘Whey proteins are also rich in the sulfur-containing amino acids cysteine and methionine.’
- ‘The gelatinase activity was due to metalloproteinases and not cysteine or serine proteinases.’
- ‘The integration of reduced sulphur into the amino acid cysteine is a central step in the assimilation of inorganic sulphur.’
- ‘Most of the sulfate substrate comes from sulfoxidation of the amino acid cysteine.’
- ‘As long as the supply of methionine is adequate, cysteine is considered as nonessential.’
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