Cysteine takes its name from cystine, named after the Greek kustis meaning bladder – cystine was first isolated for kidney stones.
Cystine is the stable form of the sulfur rich amino cysteine. The body is capable of converting one of the other as required.
The sulfur in cysteine molecules plays a crucial role in folding proteins into their correct shapes. For examples sulfur independent proteins are keratin – part of hair, skin and nails and collagen – part of connective tissue like cartilage.
Though sulfur itself does not improve nail growth it was found that cystine may have a positive effect on the growth of hypnochium cells.
The amino acid contains a sulfur group that help to function as antioxidant. Cysteine also can be combined with glutamic acid and glycine in liver cells to form glutathione, which is a principle water soluble antioxidant in cells and the blood.
The human body synthesizes the amino acid cysteine for homocysteine and it is part of human hair, skin and nails as the protein keratin.
Cysteine can be found in red pepper, garlic, onions, broccoli, brussel sprouts, oats and wheat germ.
Amino acid cysteine