The goals of Extraction and Clarification are:

  • The preparation of a clarified sample of soluble protein from the source material for further purification.
  • Removal of particulate matter or other contaminants which are not compatible with chromatography (e.g. DNA and lipids).

The necessary procedure to reach these goals depends on the origin of the sample. In the simplest case where the target protein is secreted into the culture media centrifugation or filtration will be sufficient to yield a clarified sample for the first chromatography step. Usually, however, we need to extract the protein from the host cells in which it has been expressed. A variety of methods are available to lyse cells. Which of these methods we should use in a specific case depends on the type of host cells and on the quantity of cells to be lysed.

The chapters in the left menu deal with the background and practical aspects (including protocols) of the different steps in Extraction and Clarification.

References and for further reading

Guide to Protein Purification (M.P. Deutscher, ed), Academic Press, 1990.
Protein Methods (D.M. Bollag, M.D. Rozycki, S.J. Edelstein, eds), 2nd ed., Wiley-Liss, New York, 1996.
Protein Expression. A Practical Approach (S.J. Higgins and B.D. James, eds), Oxford University Press, Oxford, UK, 1999.
Protein Purification. Amersham Pharmacia Biotech handbook, 1999. The Recombinant Protein Handbook.