Protein Determination

Publisher Summary This chapter focuses on three techniques that can be used to determine the protein content of tissues or samples. The three techniques include Lowry Assay, Bradford Assay, and Neuhoff Assay. All assays described in this article quantitate protein relative to a standard protein. The choice of the standard protein can markedly influence the result. This requires special attention for proteins with a high content of certain amino acids. The most efficient way to prepare an exact dilution series of the standard protein employs a handheld dispenser. Many reagents used commonly in protein extraction interfere with Lowry assay. The dot-blot assay is a versatile tool. Its different modifications enable one to cope with almost every potentially interfering substance. The dot-blot assay combines high sensitivity, an extended range of linearity, and high tolerance to potentially interfering substances. The Lowry assay exhibits the best accuracy with regard to absolute protein concentrations due to the chemical reaction with polypeptides. It is also useful for the quantitation of oligopeptides.