Sulphur containing amino acid is: (A) Cysteine, (B) Lysine, (C) Arginine, (D) Phenylalanine
Answer is A. (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.