Pierce™ Bradford Protein Assay Kit

The Pierce Bradford Protein Assay Kit is a ready-to-use, stable formulation of the traditional Bradford assay reagent for measurement of total protein concentration compared to a protein standard. The kit includes Bradford Protein Assay Reagent and a package of Albumin Standard ampules.

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The Pierce Bradford Protein Assay Kit is a ready-to-use formulation of the popular assay reagent originally described by Bradford in 1976. When mixed with a protein solution, the acidic Coomassie-dye reagent changes color from brown to blue in proportion to the amount of protein present in the sample. Protein determinations are made by comparison to the color response of protein assay standards, usually prepared as a series of known dilutions of bovine serum albumin (BSA) or bovine gamma globulin (BGG). The simple procedure is adaptable to nearly any volume scale, including test tubes, cuvettes, and microplates. The protein assay is compatible with most salts, solvents, buffers, thiols, reducing substances, and metal chelating agents encountered in protein samples.

Features of the Bradford Protein Assay Kit include:
• Bradford reagent—stable, ready-to-use kit of the classical Bradford assay reagent
• Colorimetric—measure with a standard spectrophotometer or plate reader at 595 nm
• Easy to use—single reagent; no working reagent preparation required
• Fast—almost immediate color development; add, mix, and read results
• Assay range—detects protein concentration in the range 1 to 1500 μg/mL
• Flexible—microplate and cuvette protocols provided and adaptable to several target working ranges

How the Bradford Assay detects protein
Development of color in Coomassie dye-based (Bradford) protein assays has been associated with the presence of certain basic amino acids (primarily arginine, lysine, and histidine) in the protein. Van der Waals forces and hydrophobic interactions also participate in the binding of the dye by protein. The number of Coomassie dye ligands bound to each protein molecule is approximately proportional to the number of positive charges found on the protein. Free amino acids, peptides, and low molecular weight proteins do not produce color with Coomassie dye reagents. In general, the mass of a peptide or protein must be at least 3,000 daltons to be assayed with this reagent.

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