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Protocol prepared by Lori Kohlstaedt, June 2006; revised April 2008.

  1. Add 100% (w/v) TCA (trichloro acetic acid, see preparation method below) to the sample to bring the TCA concentration to 20%.
  2. Incubate on ice for at least 1 hr. Dilute samples may be left overnight.
  3. Spin at maximum speed at 4 degrees in a microcentrifuge for 10 min.
  4. Wash the pellet 3X with a solution of ice cold 0.01 M HCl / 90% acetone. 5. Allow the pellet to air dry.

The pellet can then be resuspended directly in 100 mM tris, pH 8.5, 8 M urea for enzymatic digestion for mass spectrometry

Preparation of 100% TCA:

(Don’t try to weigh out TCA; it’s too hygroscopic)

  • Obtain a fresh bottle of crystalline TCA.
  • Read the weight in the container from the label.
  • Add distilled water to give a 100 g / 100 ml solution at final volume. Store the solution in an acid compatible container.

You may also access this protocol via a PDF for easy printing.