1. Add equal volume of 40% TCA.

2. Precipiate at 4 °C for 1 hour.

3. Centrifuge for 10 minutes at 4°C and carefully remove and save supernatant.

4. Wash pellet gently with cold 100% acetone (-20 °C) four times.

5. Dry sample briefly under vacuum and store sealed at -20 °C.