Rashmi,
There are other membrane materials which might bind less. We have also found that there seems to be binding sometimes to the plastic itself. So a different manufacturer can help. Also, always use same centricon for same protein. Sometimes you take a big hit on a centricon's first use and then it is fine for subsequent uses. If the protein prep is not terribly difficult, you could try that centricon a second time. We have used PEG 20 K to pull water out. If you do that you must watch it carefully and immerse the dialysis tubing in final buffer when you are near final concentration. If you just remove the PEG without washing it will continue to concentrate. Doug Ohlendorf From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of rashmi panigrahi Sent: Saturday, January 28, 2012 9:55 AM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] protein lost on membrane of centricon!! Hi all, I tried to concentrate my protein using vivaspin 20 10,000 MWCO PES. The protein was in 50mM Hepes pH 7.5, 500mM KCl and 10% glycerol. I lost about 90% of my protein on the membrane of the centricon. Please suggest some way of concentrating this protein. Will concentrating using peg 20K be a good alternative?? regards rashmi
