What is cysteine/cystine?!
What is cysteine/cystine?
Answers:
Cysteine is a naturally occurring, sulfur-containing amino acid that is found in most proteins, although only in small quantities. Cysteine is unique amongst the twenty natural amino acids as it contains a thiol group. Thiol groups can undergo oxidation/reduction (redox) reactions; when cysteine is oxidised it can form cystine, which is two cysteine residues joined by a disulfide bond. This reaction is reversible: as reduction of this disulphide bond regenerates two cysteine molecules. The disulphide bonds of cystine are crucial to defining the structures of many proteins.
Cysteine is often involved in electron-transfer reactions, and help the enzyme catalyse its reaction. Cysteine is also part of the antioxidant glutathione.
N-acetyl-L-cysteine (NAC) is a form of cysteine where an acetyl group is attached to cysteine's nitrogen atom and is sold as a dietary supplement. Cysteine is named after cystine, which comes from the Greek word kustis meaning bladder ? cystine was first isolated from kidney stones.
Also known as l-cystine, our research indicates that the source of cysteine is human hair. Cystine is an amino acid needed by humans, which can be produced by the human body. A very small quantity is used in less than 5% of all bread products. Often the hair of third world women is used.