Protein Precipitation Protocols

TCA-DOC

For precipitation of very low protein concentration

1)To one volume of protein solution,add 1/100 vol.of 2% DOC (Na deoxycholate,detergent).

2)Vortex and let sit for 30min at 4ºC.

3)Add 1/10 of Trichloroacetic acid (TCA)100% vortex and let sit ON at 4ºC (preparation of 100% TCA: 454ml H₂O/kg TCA.Maintain in dark bottleat 4ºC.Be careful,use gloves!!!).

4)Spin 15min 4ºC in microfuge at maximum speed (15000g).Carefully discharge supernatant and retain the pellet: dry tube by inversion on tissue paper (pellet may be difficult to see).

[OPTION: Wash pellet twice with one volume of cold acetone (acetone keep at -20ºC).Vortex and repellet samples 5min at full speed between washes].

5)Dry samples under vaccum (speed vac)or dry air.For PAGE-SDS,resuspend samples in a minimal volume of sample buffer.(The presence of some TCA can give a yellow colour as a consequence of the acidification of the sample buffer ; titrate with 1N NaOH or 1M TrisHCl pH8.5 to obtain the normal blue sample buffer colour.)

PIERCE: #26800 - PAGE prepTM Protein Clean-up and Enrichment Kit (pdf)