TCA Precipitation of Proteins

Materials

 * Acetone
 * Protein sample
 * Trichloroacetic acid (TCA)
 *  Prepare a 10% solution by adding  0.1 mL of 100% TCA solution to 0.9 mL of H2O. Keep both solutions on ice. 

Method

 * 1) Add 0.11 volumes of ice-cold 100% TCA to the protein sample.
 * 2) Place on ice for 10 min.
 * 3) Add 500 µ L of ice-cold 10% TCA to the sample.
 * 4) Place on ice for 20 min.
 * 5) Centrifuge at 20,000× g for 30 min. Carefully remove the supernatant by using a pipette.  Avoid disturbing the protein pellet. 
 * 6) Add 500 µ L of acetone. Gently rock the tube once or twice to rinse the tube and the pellet.
 * 7) Centrifuge at 20,000× g for 10 min. Remove the supernatant again.
 * 8) Dry the protein pellet in a vacuum evaporator or SpeedVac (typically less than 5 min).
 * 9) Solubilize the pellet in minimum volume of buffer of choice. Sonication may be required to break the pellet into smaller pieces.