b'Estimating protein sizesProtein ladders and standardsProtein ladders, also known as protein markers or protein standards, are used to help estimate the size of proteins separated during electrophoresis. They serve as points of reference because they contain mixtures of highly purified proteins with known molecular weights and characteristics.Protein ladders are loaded onto gels alongside samples and migrate during electrophoresis at a rate that is inversely proportional to their molecular sizes. When the run is complete, the proteins will appear as separate bands in the gel. A standard curve can be constructed from the distance each marker protein migrates through the gel versus the log of its molecular weight. After measuring the migration distance that an unknown protein travels through the same gel, its molecular weight can be determined graphically from the standard curve. Modern gel documentation instruments may have software algorithms that can make these mathematical calculations significantly more convenient. More often, however, protein ladders are used as a reference to help confirm the identity of proteins of interest whose sizes are already known.Protein ladders are available with various protein molecular weight ranges and can be prestained, unstained, or labeled for different modes of detection and downstream applications. Read on to learn which protein ladder is best for your applications.Learn more at thermofisher.com/proteinladders46'