Your need: analyze proteins using the Bradford method
The Bradford method is a technique for colorimetric protein determination (by absorbance/spectrophotometry), it is based on a series of chemical reactions which result in the formation of a colored complex.
Quantify your proteins with the Bradford method
In the pharmaceutical, cosmetic, chemical and natural ingredients industries, protein quantification is an essential step in controlling the quality, compliance and performance of finished products.
The Bradford method offers a quick and simple approach to protein determination, based on a colorimetric reaction to precisely measure the protein concentration in your samples, particularly those lightly contaminated by interferents.
What is the Bradford method?
The Bradford method is a technique for measuring proteins by colorimetry (by absorbance/spectrophotometry). It is based on the binding of Coomassie blue dye G-250 to proteins in an acidic environment.
In the presence of proteins, the dye changes from its cationic form (red-brown, maximum absorption at 465 nm) to its anionic form (blue, maximum absorption at 595 nm). This blue color is stable and proportional to the quantity of proteins.
It makes it possible to determine the protein concentration of a sample from a protein standard (often BSA), with good sensitivity (µg/mL) and appreciated speed of execution.
Our services on proteins
The FILAB laboratory offers a wide range of analytical services related to proteins. These specialized services are aimed at manufacturers wishing to characterize their proteins of interest in detail.
FILAB performs protein analysis using the Bradford method
Why choose FILAB for protein analysis using the Bradford method?
At the FILAB laboratory, we provide pharmaceutical, cosmetics and chemical manufacturers with comprehensive analytical expertise for protein quantification and characterisation. FILAB offers tailor-made solutions for protein analysis: dosage, contaminant identification and structural characterisation, supported by cutting-edge technologies (LC-MSMS, HPLC, UPLC-UV, etc.).
What are the main advantages of the Bradford method?
This is one of the fastest and easiest dosing methods to implement, requiring no heating.
It is very sensitive, allowing the quantification of proteins at concentrations on the order of µg/mL.
Unlike the Lowry method, it is generally little affected by reducing agents, chelating agents and certain sugars.
FAQ
The Bradford assay relies on the Coomassie blue dye. In acidic media, this dye exists primarily in two forms:
- The cationic form (reddish-brown) in the absence of protein (absorption at 465 nm).
- The anionic form (blue) in the presence of protein. The binding of the dye to basic and aromatic amino acids (such as arginine) stabilizes this blue form, whose maximum absorption is measured at 595 nm. The intensity of the blue color is directly proportional to the protein concentration in the sample.
The absorbance of the protein-dye complex (the blue form) is measured by spectrophotometer at 595 nanometers (nm).
Protein variability means that the amount of blue color produced is not only proportional to the total protein mass, but also to the protein's amino acid composition. Proteins rich in basic amino acids (arginine, lysine, histidine) and aromatic amino acids (tyrosine, tryptophan) induce a more intense color response than others. Consequently, equal amounts of two different proteins can yield two different absorbances, necessitating the use of a reference standard (such as BSA) to calibrate the results.
