Soluble protein extraction



Hendrik Poorter & Yvonne de Jong-Van Berkel

Author Affiliations

Hendrik Poorter IBG-2, Forschungszentrum Jülich

Yvonne de Jong-Van Berkel, Ecophysiology of Plants, Faculty of Science, Utrecht University


Protein can be extracted from fresh plant material after removing chlorophyll and other compounds such as amino acids using 80% acetone and methanol (chlorophyll extraction) or 80% ethanol (amino acid extraction). The extraction with sodium hydroxide gives a protein extract that can be used for determination of proteins using Bradford’s method.



  • Sodium hydroxide 0.1 N


  • Water bath
  • Table centrifuge
  • Centrifuge tubes


  1. Add 5 ml 0.1 N NaOH to the pellet after a macro chlorophyll extraction or 0.5 ml 0.1 N NaOH after a micro chlorophyll extraction (see Chlorophyll extraction and determination ).
  2. Mix thoroughly and put the test tubes in a waterbath of 70C.
  3. Centrifuge for 10 minutes at high speed in a table centrifuge (4500 rpm – 2694 g).
  4. Decant the supernatant in a volumetric flask of 25 ml or 10 ml.
  5. Do the same extraction two more times.
  6. Fill up the volumetric flask with 0.1 N NaOH.
  7. The extract is ready for determination using Bradford’s assay (reagents and kits commercially available, method not provided here).

Literature references

Davies, E.M., 1988. Protein assays: A review of common techniques. ABL 28-37.

Tal, M., Silberstein, A. & Nusser, E., 1980. Why does coomassie brilliant blue R interact differently with different proteins. J. Biol. Chem. 260: 9976-9980.

Sedmak, J.J. & Grossberg, S.E., 1977. A rapid sensitive and versatile assay for protein using coomassie brilliant blue G250. Anal. Biochem. 79: 544-552.

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