The Catalytic Role of L-Cysteine in Organic Reactions
48–74
چکیده
Methionine and cysteine are two of the most representative sulfur amino acids which play a very important role in biological systems. Its intrinsically unstable nature usually exists in proteins as a cystine by forming a disulfide bond. Methionine is an essential amino acid, whereas cysteine is produced from methionine and therefore is nonessential. Cysteine is categorized as a polar, uncharged, and hydrophobic amino acid. Cysteine is classified as a semi-essential amino acid and can be synthesized in the liver from methionine, which is a sulfur-containing amino acid. It is also found in many protein-rich foods and sold as a dietary supplement. Moreover, L-cysteine, or its modified form, was recently investigated as a catalyst in a wide variety of organic reactions.