P.S. I haven't personally tried concentrating with PEG 20K but I suppose it could work.
On Sat, Jan 28, 2012 at 12:41 PM, Cale Dakwar <c.dak...@gmail.com> wrote: > > Hello Rashmi, > > How large are your protein monomer units? Are you expecting these units > to have formed an oligomer? As a general rule of thumb, you want your > protein molecules to be no smaller than 3x the membrane MWCO. Perhaps all > you need is to try concentrating with a lower MWCO membrane, e.g. 3,000. > > Alternatively, you could try: > > - change membrane manufacturers (this sometimes does make a difference), > > - pretreating your membrane (e.g. with BSA) to block all binding sites > (but then you'll have to worry about BSA contamination of your sample), > > - concentrating your protein in under nitrogen pressure (I forget right > now what the device is called but I used to use it all the time), > > - concentrating your protein in a speed vac to evaporate off some of the > water, > > - ammonium sulphate precipitation, > > - or even TCA precipitation. > > HTH, > C > > > > > On Sat, Jan 28, 2012 at 10:54 AM, rashmi panigrahi < > rashmi.panigrah...@gmail.com> wrote: > >> 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 >> > >
