b'Accurate detergent-compatible Pierce BCA assaysBCA protein assays have a unique advantage over Bradford (Coomassie dyebased) assays, as they are compatible with samples that contain up to 5% surfactants (detergents) and are affected much less by protein compositional differences, providing greater protein-to-protein uniformity and accuracy (Figure 8). 1.0 Pierce Rapid Gold BCA Protein Assay0.9 Bradford Protein Assay (Bio-Rad)Concentration (mg/mL)0.8 Known concentration0.70.60.50.40.30.20.10 A B C D E F G H IProtein mixFigure 8. Accuracy of the Pierce Rapid Gold BCA Protein Assay and Bradford Protein Assay with known protein mixes. Both assays were conducted according to the respective manufacturers protocols, in a microplate format. For the Bradford assay, 10 L of the BSA sample was added to 200 L of the Bradford working reagent and incubated at room temperature for 5 minutes. For the Pierce Rapid Gold BCA Protein Assay, 20 L of sample was added to 200 L of Rapid Gold BCA working reagent and incubated at room temperature for 5 minutes. Known concentrations were based on manufacturers indicated concentrations and confirmed by absorbance at 280 nm.Broad dynamic range of the Qubit Protein BR AssayThe Invitrogen Qubit Protein BR Assay is a fluorometric assay that combines accuracy, compatibility, and ease of use to detect total protein concentrations over a broad dynamic range. The broad linear response allows accurate determination of unknown protein concentrations and provides a higher dynamic range than other standard protein assays (Figure 9). The Qubit Protein BR Assay can be used to detect protein concentrations from 100 to 20,000 g/mL and is compatible with many commonly used detergents and reducing agents. This allows most samples to be used neat (undiluted), eliminating the guesswork and dilution steps that accompany many protein quantitation methods.7.0 7,000BCA6.0 6,0005.0 5,000Absorbance RFU4.0 4,0003.0 Qubit Protein BR Assay 3,0002.0 2,0001.0 Bradford 1,0000.0 00 5,000 10,000 15,000 20,000 25,000Sample concentration (g/mL)Figure 9. Standard curves for protein quantitation assays. Purified bovine serum albumin (BSA) in 0.9% saline (020 mg/mL) was used to generate standard curves for the Qubit Protein BR Assay, Pierce BCA Protein Assay, and the Bradford assay. Assays were conducted following the manufacturers protocols. The BCA and Bradford assays were performed in microplate format.24 Protein sample preparation thermofisher.com/proteinbiology'