Bio-Gel P2, cut off 2.000 daltons?

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Discussion Overview

The discussion revolves around the concept of gel filtration and the implications of a "cut off 2.000 daltons" in relation to protein isolation. Participants explore the mechanics of molecular weight cutoffs in filtration processes and how they affect the concentration of proteins during experiments.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about the meaning of a gel filtration cutoff of 2.000 daltons, seeking clarification on its implications.
  • Another participant explains that the filter allows particles lower than 2 daltons to pass through, while those above this weight are retained.
  • A participant expresses confusion regarding the isolation of a protein with a molecular weight of 15 kDa, questioning how it can be concentrated using a filter with a 5 kDa cutoff.
  • There is a discussion about whether buffer is added during the concentration process and how that affects the protein's passage through the filter.
  • A participant clarifies that the ULTRAFREE 15 is a column with a membrane that traps proteins above a certain molecular weight, allowing for the concentration of the protein of interest.

Areas of Agreement / Disagreement

Participants express differing levels of understanding regarding the filtration process and the implications of molecular weight cutoffs. The discussion remains unresolved as participants seek further clarification and do not reach a consensus on the mechanics involved.

Contextual Notes

There are uncertainties regarding the specific mechanisms of the filtration process, including the role of added buffer and the nature of the ULTRAFREE 15 device. Assumptions about the behavior of proteins in relation to the cutoff values are not fully explored.

Who May Find This Useful

This discussion may be useful for individuals involved in protein purification, particularly those using gel filtration techniques or similar methodologies in biochemical research.

sotellme
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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!
 
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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.
 
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!
 
Last edited:
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.
 
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!
 
thanks, Ian!
 

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