<prompt> Sulphur containing amino acid isCysteineLysineArgininePhenylalanine  <response>: A Cysteine Sulfur-containing amino acids cysteine methionine are generally considered to be nonpolar and hydrophobic. In fact, methionine is one of the most hydrophobic amino acids and is almost always found on the interior of proteins. Cysteine on the other hand does ionize to yield the thiolate anion. 