Freimoser:Protocols:ProteinQuantification

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The quantification methods listed below represent those that we find most useful. The descriptions are part of a more detailed list of protein quantification methods [1]
General Reference: Stoscheck, CM. Quantitation of Protein. Methods in Enzymology 182: 50-69 (1990). [2]


Absorbance assays

Absorbance at 280 nm

  • Range: 20 μg to 3 mg
  • Volume: Depends on cuvette - volumes range from 200 microliters to 3 ml or greater
  • Accuracy: Fair
  • Convenience: Excellent, if equipment available
  • Major interfering agents: Detergents, nucleic acids, particulates, lipid droplets

Absorbance at 205 nm

  • Range: Roughly 1 to 100 μg
  • Volume: Depends on cuvette - volumes range from 200 microliters to 3 ml or greater
  • Accuracy: Fair
  • Convenience: Very good
  • Major interfering agents: Detergents, nucleic acids, particulates, lipid droplets


Colorimetric assays

Modified Lowry

  • Range: 2 to 100 μg
  • Volume: 1 ml (scale up for larger cuvettes)
  • Accuracy: Good
  • Convenience: Fair
  • Major interfering agents: Strong acids, ammonium sulfate

Bradford assay

  • Range: 1 to 20 μg (micro assay); 20 to 200 μg (macro assay)
  • Volume: 1 ml (micro); 5.5 ml (macro)
  • Accuracy: Good
  • Convenience: Excellent
  • Major interfering agents: None
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