Quantification of protein concentration is a critical part of any laboratory workflow involving protein extraction, purification, labeling, or analysis. The selection of an appropriate protein assay is important. Ideally, the detection limit should be as low as possible with an optimal signal-to-noise ratio. To correctly quantify proteins in a sample, the assay should have a wide dynamic range and a broad linear relationship between the amount of protein and the intensity of staining. The assay procedure should be easy to perform quickly, non-toxic, environmentally friendly, and not too expensive. However, there is no single protein detection technique that meets all of these requirements. Therefore, it is necessary to choose the optimal method based on the research purpose, sample type, and other methodical requirements.
Based on a variety of methods that have been developed to quantify proteins, a wide range of protein assay and quantification kits are available for the rapid detection of protein abundance or concentration. The bicinchoninic acid (BCA) assay, a copper-based colorimetric assay, is one of the most popular methods for total protein quantification. BCA assay is less variable and less susceptible to detergents than Bradford assay, while Bradford assay has a simpler and faster procedure. The Bradford protein assay is a dye-binding assay based on the differential color change of a dye in response to various concentrations of protein. Staining with the organic dye Coomassie Brilliant Blue is still the most frequently employed method for protein detection in polyacrylamide electrophoresis gels. The advantages of Coomassie staining methods are the quantitative binding of the dye to proteins, the low price and the good reproducibility. The disadvantages of this staining assay are the long staining times, the relatively low sensitivity, and the narrow dynamic range. Fluorescence staining is the optimum method for combining high sensitivity of detection with reliable quantification over a wide linear dynamic range. However, the dyes are more expensive than those used for visual staining, and a fluorescence scanner is needed to visualize the spots and to acquire the image for image analysis. Lateral flow immunoassay (LFI), also called immunochromatography, is a membrane-based technique used to detect the presence of specific protein in fluid. The advantages of LFI include one-step and low-cost analysis, very short assay time, and no requirement for expensive equipment or highly skilled technicians.
Amerigo Scientific offers a wide range of simple, reliable assay kits for protein quantification or semi-quantification via fluorescence, colorimetric, or other assays to meet different research needs.
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