Price $170
Product Description: Protocol Download
The detergent compatible Protein Assay Kit combines two famous reactions- the Biuret reaction and the Smith reaction. The Biuret reaction depicts the reduction of cupric ion (Cu2+) to cuprous ion (Cu1+) by protein in an alkaline solution. The intensity of the reaction is proportional to the number of peptide bonds (at least 2 peptide bonds) and therefore to the number of protein molecules present in the sample solution. The Smith reaction depicts the chelation of each Cu1+ ion by two molecules of bicinchoninic acid (BCA), resulting in an intense purple-colored product that absorbs light at 562 nm (Anal. Biochem. 150: 76–85, 1985), which can be measured with a standard laboratory spectrophotometer or microplate reader. Unlike the dye-based protein assay system, the BCA-based protein assay system is compatible with detergent-containing protein samples. However, the BCA assay is incompatible with most divalent ions. Prepare fresh working solution by mixing 50 parts of BCA Solution with 1 part of Copper Solution (50:1). The Protein Assay System has a broad working range of 20 – 2000 ug/ml proteins. The assay kit also includes 1 ml of 100 mg/ml sterilized BSA dissolved in distilled water to be diluted for use as protein standard. The assay kit is stable for at least one year under proper storage and handling conditions.