Have you ever wondered why there are so many protein quantitation assays to choose from? I think I ask myself this question every time I need to use one! Accurate determination of protein concentration is critical for many experiments. Unfortunately, many of the detergents and reducing agents used to extract proteins are incompatible with the various protein quantitation assays. Before selecting an assay, you will need to know the composition of your sample’s buffer to help you decide which is best. The most common protein assays are summarized in Table I.
If you are still having a hard time finding an assay that will meet your sample’s needs, consider dialyzing or desalting your protein into a suitable buffer. If your protein is at a high enough concentration it is also acceptable to dilute your sample into an appropriate buffer. Check out the user manual that comes with your favorite protein assay to determine the maximum level of interfering substance that can be tolerated.
G-25 Desalting Spin Columns