The Bradford protein assay is a spectroscopic analytical procedure used to measure the concentration of protein in a solution. The Bradford protein assay was developed by Marion M. Bradford, is based on an absorbance shift of the dye Coomassie Brilliant Blue G-250 in which under acidic conditions the red form of the dye is converted into its bluer form to bind to the protein being assayed. This very sensitive colorimetric assay has an absorptions maximum at 595nm and detection limit is 0.01mg protein / ml. Unlike other protein assays, the Bradford protein assay is less susceptible to interference by various chemicals that may be present in protein samples. An exception of note is elevated concentrations of detergent (e.g. SDS).
BCA (Bicinchoninic acid assay) is a spectroscopic analytical procedure used to measure the concentration of protein in a solution. The BCA protein assay was developed by Paul K. Smith, is based on the reduction on Cu2+ ions from the cupric sulfate to Cu+. The amount of Cu2+ reduced is proportional to the amount of protein present in the solution. Next, two molecules of bicinchoninic acid chelate with each Cu+ ion, forming a purple-colored product that strongly absorbs light at a wavelength of 562 nm. The detection limit is 0.005 mg protein / ml. The test is very stable to most buffer and detergents, but small amount of reducing or chelating substances interfere with the test.
Amino acid analysis (through partner)