gel filtration vs dialysis

Artem Evdokimov AEVDOKIMOZ at cinci.rr.com
Tue Jan 8 22:21:04 EST 2002


Simply put, it won't work. Several reasons, some of which relate to the fact
that m.w. cutoff of dialysis tubing isn't just a 'size of hole'. Other
reasons relate to the fact that proteases tend to stick to other proteins,
for obvious reasons. Also, equilibration time is a killer - on a size
exclusion you get many orders of magnitude better separation, and faster
too.

A.G.E.

"Dominic-Luc Webb molmed" <domweb at mbox.ki.se> wrote in message
news:Pine.GSO.4.43.0201081622320.22958-100000 at mbox.ki.se...
>
> I want to get rid of proteases, mainly from an E coli
> expression system in which I am expressing an 86 KD
> protein (mammalian). The bacterial homolog is 32 KD
> and I also want this removed. This seems like classical
> job for gel filtration, but I am thinking that maybe
> the Spectra/por 6 or 7 RC dialysis tubing with 50 KD MWCO
> might work better (like preserving the volume) or
> maybe it would give better/faster separation. My
> understanding from reading is that bacterial proteases
> are typically very small, and well below this 50 KD
> MWCO.
>
> Could someone please tell me if this is not such a
> clever idea and why or why not?
>
>
> Cheers,
>
>
> Dominic
>
> North 59 37' 30"
> East  17 48' 10"
>





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