Merck, C7661-100MG, Collagen from rat tail

All collagen molecules are composed of three polypeptide chains arranged in a triple helical conformation, with a primary structure that is mostly a repeating motif with glycine in every third position and proline or 4-hydroxyproline frequently preceding the glycine residue. Type I collagen differs from other collagens by its low lysine hydroxylation and low carbohydrate composition. Col1a1 (collagen, type I, α1) or collagen is a major structural human protein, which assembles in the form of fibrils. It is a very long, thin and the most abundant protein found in the human body. It is a supercoiled right-helix of three left-handed polypeptide chains. These chains are composed of ~1040 amino acids, which are essentially repeats of three amino acids -(Gly-X-Y)n. Gly is glycine and X and Y can be any amino acids, but in humans are usually proline and hydroxyproline, respectively.