Calibration curve Bradford protein assay

Protein concentration was determined using the Bradford assay at 595 nm. 100 pL of the sample were introduced into a cuvette containing 5 mL of Bradford solution (100 mg of Coomassie blue, 50 mL of ethanol and 100 mL of 85 % phosphoric acid dissolved in 850 mL of H2O). The solutions were incubated for 5 min at room temperature. The absorbance was measured at 595 nm. The protein concentration in the sample was determined using a calibration curve plotted with serum albumin (1 mg mL ) as a standard.)... 

Standard calibration curve for the Bradford assay using bovine gamma globulin as standard protein. 

The Lowry, Smith, and Bradford assays provide an estimate, rather than an exact measure of total protein. Why What is the importance of the standard protein chosen for the construction of calibration curves ... 

Using a Bradford assay, determine the protein concentration of the P2 fraction, which was previously resuspended in isolation buffer. To do this, mix 799 //I water with 1 //I P2 and add 200 /il Bio-Rad Protein Assay reagent (Hercules, CA). Incubate for 5 min at room temperature and determine the absorbance at 595 nm. To convert the absorbance value to protein concentration, make a calibration curve with a series of known concentrations of bovine serum albumin. Adjust the concentration of the P2 suspension to obtain 1 mg protein/100 /il solution. 

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