How can I desalt and concentrate a protein fraction by trichloroacetic acid (TCA) precipitation?
1. Dilute samples to at least 100 µl, add equal volumes of 10% TCA.
2. Leave on ice for 20 min; centrifuge for 15 min in a microcentrifuge at full speed.
3. Wash pellet with 100 µl ice-cold ethanol, dry, and resuspend in sample buffer.
This precipitation method results in denatured proteins. In case there are any traces of guanidine hydrochloride present, samples should be loaded immediately after boiling for 7 min at 95°C onto a gel for SDS-PAGE.