Precipitating Proteins

TCA precipitation

Dissolve 20 ml of sample in 180 ml 25 % TCA. Let incubate on ice for 15 min. Spin for 15 min at 14000 / min; discard the supernatant. Do not use the speedvac! Wash with 5 % TCA, spin again. Redissolve in 20 ml water and adjust pH with some crystals of Tris.

Add TCA to sample in order to reach 7% final concentration: 30 min 4°C; spin 15 min at 14000 / min

Acetone-precipitation

Dissolve 20ml of sample in 180ml acetone. Do not forget to vortex! Let incubate at -20°C for at least 1 h. Spin at maximum speed and dry the pellet in the speedvac. Optionally, add three drops of glacial acetic acid per 180 ml of acetone. Wash the pellet with pure acetone, redissolve in a proper volume of water.

Ammonium sulfate precipitation

Dissolve 20 ml of sample in 180 ml of saturated ammoniumsulfate. Icubate on ice for 30 min. Spin for 15 min at 14000 /min. discard the supernatant and redissolve in 20 ml water.