Opal Prestained Protein Standard 10-245kDa contains approximately 0.1-0.4 mg/ml of each protein in the buffer (20 mM Tris-phosphate, pH 7.5 at 25°C), 2 % SDS, 1 mM Dithiothreitol, 3.6 M Urea, and 15 % (v/v) Glycerol). Opal Prestained Protein Standard 10-245kDa is a three-color protein standard with 12 pre-stained proteins covering a wide range molecular weights from 10 to 245 kDa. Proteins are covalently coupled with a blue chromophore except for two reference bands (one green and one red band at 25 kDa and 75 kDa respectively) made visible when separated on SDS-PAGE (Tris-glycine buffer). Opal Prestained Protein Standard 10-245kDa is designed for monitoring protein separation during SDS-polyacrylamide gel electrophoresis, verification of Western blot transfer efficiency on membranes (PVDF, nylon, or nitrocellulose) and for approximating the size of proteins.