Description_x000D_ Packaging_x000D_ 1, 5 mg in glass bottle_x000D_ Components_x000D_ 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._x000D_ Caution_x000D_ This product should be stored desiccated at -20°C, and will retain activity in these conditions for 3 years._x000D_ Preparation Note_x000D_ This product was prepared by a modification of the pepsin extraction and salt fractionation method of Niyibizi, C., et al., J. Biol. Chem., 259, 14170 (1984). It is an acid soluble collagen that can be dissolved in water with acetic acid added to pH 3.0 (5 mg/mL), yielding an opalescent, colorless solution._x000D_ Analysis Note_x000D_ An SDS polyacrylamide gel electrophoresis test run under reducing conditions consistent with basement membrane collagen yields three major bands._x000D_ Other Notes_x000D_ Collagen is classified into a number of structurally and genetically distinct types. We use the nomenclature proposed by Bornstein and Traub. Be wary of confusing Sigma-type designations with recognized collagen classification types.