Bio-Gel P2, cut off 2.000 daltons?

[sotellme]

hello everybody!

what does it mean when a gel you use in gel filtration has a "cut off 2.000 daltons" ? i have looked for the answer, but can't find it.

hopes for replies!

many thanks!

[iansmith]

It means that the filter will only let particle lower than (more or less) 2 dalton to pass through. Anything higher than 2 dalton will not pass.

[sotellme]

hi Ian!

thanks for your reply, but i still don't get it. our protein (which we has to isolate) has a MW 15kDa. before we running the sample on a gel filtration, we concentrated the sample using a ULTRAFREE 15 from MILLIPORE "CUTOFF" 5kDa. as you said components at this MW or less will go through, but higher MW won't pass. then how come i concentrate my protein, when it does not pass through? :confused:


p.s "to pass through" do you mean passing through the gel's pores?

thanks again!

[iansmith]

When you the utrafree to you add buffer to the filter or do you take the supernantant. If you add buffer/liquid to colum then the your protein did not pass the cut off.

[sotellme]

well we added our sample to this kit...

by the way is this ULTRAFREE 15 from MILLIPORE "CUTOFF" 5kDa a gel or just a paper filter? a weird question since i did take the course! :grumpy:

[iansmith]

http://www.millipore.com/userguides.nsf/docs/p35741?open&lang=en

The utrafree-15 is column with a membrane/filter which trap protein above a certain molecular weight. You then resuspend that concentrate which is your protein. The flow thru does not have any protein of interest.

[sotellme]

thanks, Ian!