Protein Concentration from Medium - (Mar/30/2002 )

I would need a protocoll for concentration of proteins from Medium.
In the Bradford assay i could not detect a protein concentration.

Hye

Try a dyalise with a down cut off (7000Da). After you put samples in freeze and lyophise. After you wil have a powder.
Bye

Trichloroacetic acid (TCA) precipitation is easy. I add 0.5ml of 10%TCA to 1ml of medium in an eppendorph, leave on ice for 20-30 mins then centrifuge for 15mins in a microcentrifuge at 13000rpm. Discard the supernatant and resuspend the pellet (not always visible) in 20microlitres of water or buffer. This will give you a 50x concentration.