2003, Agrawal and Thelen 2009), which are of special interest to researchers working in the life sciences (examples include Pro-Q Diamond and Pro-Q Emerald). 2003) and phosphoproteins (Steinberg et al. Specific protein stains are used to visualize specific protein classes such as glycoproteins (Hart et al. Right: Protein gel imaged using stain-free technology. Left: the ChemiDoc Touch System comprises the imager with UV/stain-free tray and Image Lab Software. Learn more about the advantages of using stain-free technology.īio-Rad's ChemiDoc Touch Stain-Free Enabled Imaging System. Total protein normalization is becoming the gold standard for western blotting normalization in major peer-reviewed journals. Using a stain-free enabled imager, total protein normalization can be performed on posttransfer membranes, allowing for precise quantitation of western blotting signals. Stain-free technology also offers tremendous advantages in quantitative western blotting experiments. 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 enables the visualization of proteins in gels and on membranes without a staining step and provides several advantages over conventional staining procedures.

Examples include Flamingo™ and Oriole™ Fluorescent Gel Stains. For these reasons, fluorescent stains are often used in proteomics applications and on 2-D gels, where the relative quantitation of proteins in complex mixtures over several orders of abundance is performed and protein identity is determined using in-gel proteolytic digestion and mass spectrometry. In comparison to Coomassie or silver staining techniques, however, fluorescent dyes are more expensive and require either a CCD (charge-coupled device) camera or fluorescence scanner for gel imaging. These stains fulfill almost all the requirements for an ideal protein stain by offering high sensitivity, a wide linear dynamic range over four orders of magnitude, a simple and robust protocol, and compatibility with mass spectrometry. Silver stain offers sensitivity that exceeds that of Coomassie and is equivalent to most fluorescent stains. In addition, their compatibility with mass spectrometry for protein identification purposes is lower compared to Coomassie stains and fluorescent dyes (Yan et al. Often, these protocols are time-consuming, complex, and do not offer sufficient reproducibility for quantitative analysis. Silver stains offer the highest sensitivity, but with a low linear dynamic range (Merril et al. It offers a sensitivity that is better than conventional Coomassie R-250 formulations and equivalent to Coomassie Blue G-250, but with a simpler and quicker staining protocol. Bio-Safe Coomassie Stain is a nonhazardous formulation of Coomassie Blue G-250 that requires only water for rinsing and destaining. Coomassie dyes are also the favorite stains for mass spectrometry and protein identification. There are two variants of Coomassie Brilliant Blue: R-250 (R for reddish), which offers shorter staining times, and G-250 (G for greenish), which is available in more sensitive and environmentally friendly formulations (Simpson 2010, Neuhoff et al. The most popular anionic protein dye, Coomassie Brilliant Blue, stains almost all proteins with good quantitative linearity at medium sensitivity. The table below compares the advantages and disadvantages of several total protein staining techniques.

Total protein stains allow visualization of the protein pattern in the gel.

Membrane pro reagent