What method is commonly used for detecting protein concentration in a fluorescent tag like GFP?

The Bradford assay is a widely utilized method for detecting protein concentration, making it particularly suitable for proteins labeled with fluorescent tags such as GFP. This assay is based on the binding of Coomassie Brilliant Blue dye to protein molecules, resulting in a color change that can be quantitatively measured using a spectrophotometer. The intensity of the blue color is directly proportional to the amount of protein present in the sample.

One of the reasons the Bradford assay is often favored is its simplicity and speed. It requires minimal sample preparation and can provide results in a relatively short time frame. Additionally, the assay is effective across a variety of protein concentrations and is compatible with many common buffers, which is crucial when working with fluorescent proteins that might require specific buffer conditions.

While other methods such as the BCA assay, Western blotting, and ELISA are valuable techniques in protein analysis, they have different applications. The BCA assay, for example, involves a colorimetric reaction dependent on the number of reducing agents present and is not as straightforward as the Bradford assay for initial protein concentration measurements. Western blotting is primarily used for protein identification and quantification following separation by gel electrophoresis, while ELISA is mostly employed for detecting specific proteins or antigens rather