I have happily been running E. coli membrane proteins on 10% polyacrylamide gels with 7M urea...until recently. The
samples run AOK on just SDS gels, but with the addition of urea, I am getting little streaky triangular shaped bands
(pointy side up). I have tried different batches of urea, but it doesn't help the problem. The only thing that I can think of that has changes is that I am using a different power pac. I was using a biorad powerpac 300, and am now using a power pac 1000 (but
I am using the same mA etc (25mA)).
Any suggestions greatfully appreciated!