होमोसिस्टिन

Also known as Hcy, 2-amino-4-sulfanyl-butanoic acid, 2-amino-4-mercapto-butyric acid, 2-amino-4-mercaptobutanoic acid, 2-amino-4-sulfanylbutanoic acid, Usaf B-12, DL-2-Amino-4-mercaptobutyric acid, (+-)-homocysteine

Homocysteine (; symbol Hcy) is a non-proteinogenic α-amino acid. It is a homologue of the amino acid cysteine, differing by an additional methylene bridge (). It is biosynthesized from methionine by the removal of its terminal Cε methyl group.