Gels keep cracking

Sam Michaelson sam.michaelson at dsto.defence.gov.au.ANTISPAM
Sun Nov 29 18:04:24 EST 1998


S. McKay wrote:

>        I've been having some problems drying mini-gels.  I'm using 14%
>
> SDS-PAG to separate my protein (which is 35S-labelled).  Following
> this I
> have been fixing the gels in 7% Acetic Acid for 20', rinsing in dH2O
> and
> then an amplification step using 0.5M Salicylic Acid for 20'.  The
> gels are
> then dried onto Whatmans 3mm Chromatography Paper under vaccum and
> heat on
> a BioRad Gel Slab Dryer for 1.5hrs.  Less time than this and the
> centre of
> the gels do not dry.  Unfortunately, I've been experiencing severe
> cracking
> problems with the gels which is obviously unacceptable.

I haven't run mini gels for a couple of years now, but I do remember
throwing the odd screaming fit trying to dry them down. I was drying
down 12% SDS-PAGE gels that were 0.75 or 1.5 mm thick (BioRad
Mini-Protean II apparatus).  Through a series of trials and
observations, I found out that I got the best results by:

1) allowing gels to resaturate fully in water (tried various glycerol
concentrations up to 10% to no avail)

2) this seemed to do the trick: try not turning on the heater
immediately on the gel dryer.  I found that by allowing the gel to
flatten and dehydrate a bit without the heater, then increasing the heat
gradually, I usually got quite a good result.  Yes, it took a bit
longer, but for my gels, it seemed to stop them cracking.

This assumes, of course, that your gel dryer is fully functional.  Does
the gel crack no matter where on the screen you place it?  Do everyone
else's gels crack, too?  (I ask because we had a certain amount of
trouble with a gel dryer that was not creating an even vacuum over the
whole surface - once we cleaned that up, it worked fine).

Good luck

Sam Michaelson






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