Combining gel filtration and electrophoresis
Austin P. So (Hae-Jin)
nobody at nowhere.com
Wed Feb 1 18:11:59 EST 2006
Daniel Käsmayr wrote:
> What I would like to have is a system that uses electric charge to
> drive particles, but also a matrix that retards smaller particles much
> more than larger ones; resulting in something like an inverse- PAGE,
> where larger particles migrate faster than smaller ones.
> The substances that need to be characterized are star polymers / brush
> polymers that have multiple functional groups (amine or carboxylic
> acids) which are used to create peptide bonds to make conjugates with
> DNA and/or Proteins.
> What would also help is some sort of modification I could do to PAGE
> that would help me get my star-shaped polymers (and their conjugates
> with proteins or DNA) into the gel. Right now it seems like I either do
> not get them to penetrate the gel matrix (I see only some residues on
> the gel pocket's outside and just a few mm inside the gel - these are
> 3% gels already and ver un-handlable) or they are not stainable with a
> silver stain
> From my syntheses I know the polymers can be analyzed by GPC/SEC - but
> I don't have enough material for this anymore - DNA is very expensive
> if you are talking about mg amounts.
Hmmmm...I don't get it since there is no apparent reason (at least to
me), why you need to fractionate things in the reverse manner...do you
need to retain the larger products? Is there a reason why
membrane-fitration at a specific MWCO wouldn't work?
BTW, DNA is probably the cheapest thing to obtain in mg quantities.
Nonetheless, one way that I can think of is a method that was developed
by a professor out here at UBC:
Basically, they exploit the fact that there is a non-linear relationship
between size and electrophoretic velocity, so that basically you can
encourage the migration of large fragments of DNA.
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