Following electrophoresis, protein band patterns can be visualized and subjected to qualitative and quantitative analysis. Protein visualization is usually achieved through use of protein stains. Once the gel is stained, it can be photographed and analyzed using imaging instruments and accompanying software.
Related Topics: Protein Electrophoresis.
Gels are run for either analytical or preparative purposes. The intended use of the gel determines the amount of protein to load and the means of detection. It is most common to make proteins in gels visible by staining them with dyes or metals. Each type of protein stain has unique characteristics and limitations with regard to sensitivity of detection and the types of proteins that stain best. Select protein stains based on their properties and your intended applications.
Often proteins are transferred to membranes for western blotting or other applications. Protein blots can also be visualized using stains. Find more information on blot detection and imaging in the western blotting section.
Stain-free technology enables the visualization of proteins in gels and on membranes without a staining step and provides several advantages over conventional staining procedures. In particular, it eliminates the need for a lengthy destaining step, which makes visualization faster and more efficient and eliminates the need to dispose of organic waste generated during destaining.
Stain-free technology also offers tremendous advantages in quantitative western blotting experiments. Using a stain-free enabled imager, total protein normalization can be performed on posttransfer membranes, allowing for precise quantitation of western blotting signals. Total protein normalization is becoming the gold standard for western blotting normalization in major peer-reviewed journals.
Before gels can be analyzed with an image evaluation system, they must be digitized. Digitization of gels stained with colorimetric, fluorescent dyes or radioactive compounds requires specific imaging systems (Patton 2000). The most commonly used devices are camera systems, densitometers, phosphor imagers, and fluorescence scanners. All of Bio-Rad's imaging systems are seamlessly integrated with analyis software (Image Lab™ and PDQuest™ software), and they can export and import images to and from other software via TIFF files.