The extract will contain a complex mixture of all the proteins from the cell cytoplasm, and some additional macromolecules, cofactors and nutrients. Crude protein extracts are prepared by removal of cellular debris generated by cell lysis, which is achieved using chemicals and enzymes, sonication or a French Press. The debris are removed by centrifugation and the supernatant is recovered. Crude preparations of extracellular proteins may be obtained by simply removing the cells by centrifugation.

Removal of denatured proteins