Poser for PAGEophiles

Rick Conrad rconrad at bio.indiana.edu
Fri Mar 24 16:04:27 EST 1995


I don't know if there is a solution to this, but here's the problem:
I've set a up a 10% polyacrylamide gel in 7M urea and 40% formamide. 
I've been able to use these sorts of gels (at 6% and 8% acrylamide)
to eliminate compressions on sequencing gels before.  The method is 
outlined in the Red Book in the DNA sequencing chapter.  However, when
I ran the 10% gel, I got a squashing of both tracking dyes as well as
the nucleic acid I was separating at the putative salt front.  Here 
some salient points:
-the gel has 1XTBE in it
-the current draw for the voltage used is within reason
-pre-running the gel seems to alleviate the problem
-pH is the same for the electrode buffer and gel solution
-resistance is ~2000 ohm for the electrode buffer and ~3000 ohm for the gel
sol'n
-two separate poymerizations of the same gel solution, with different APS
solutions, give the same screwy results

Any ideas out there?




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