What are the common standards used for the Bradford assays?

Bovine serum albumin (BSA) and bovine γ-globulin (BGG) are the two most common standards used for the Bradford assays. The Bradford assay, which is a technique used to measure protein concentration in a solution, is dependent on the amino acid composition of the measured proteins. The standards serve two purposes in the Bradford assay. They help to quantify the protein content in the sample and eliminate any background that can interfere with the results. Using a standard that has similar properties to the protein in the sample gives the most accurate protein estimation. However, because this can be difficult or even impossible for most samples being analyzed, using readily available protein standards such as BSA and BGG has become more acceptable. Bradford protein assays do show significant protein-to-protein variation when using these standards. To compensate for this variation, the calculated result is considered as an estimation of protein concentration.