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BioRad Protein Assay

Microassay Procedure

Sensitive up to 20ug protein, or 25 ug/mL

  1. Protein sample or standard is made up to 800uL in appropriate buffer, in microfuge tubes. Typical standards are 0, 2.5, 5, 10, 20ug BSA. Often, two dilutions of the sample are tested.
  2. Add 200uL BioRad dye reagent to each tube, mix well without foaming
  3. Incubate 5min. to 1hour at room temperature (24C).
  4. Measure absorbance at 595nm wavelength (visible). Plot standard curve, A vs. ug standard, read unknowns.

Can adjust total assay volume to 0.5mL or 100uL in proportion. If measuring about 1mg protein, use 0.1mL sample with 5mL reagent, incubate and read as usual.

Concentrations of detergent higher than 0.1% and high pH levels can interfere significantly with this assay.

Also know as: Bradford assay, Coomassie Brilliant Blue G-250.