Streaking of SDS-PAGE samples:Mechanisms

Leonard Ornstein lenornst at pipeline.com
Mon Jan 27 16:23:43 EST 1997


Scott:

The prescriptions offered further down in this thread as a CURES, should 
be useful answers to your first question.

I'll try to answer you second:

At high voltage gradients, high-molecular weight aggregates (e.g., of 
DNA and protein) tend to get driven into under-sized pores, to strech 
the gel locally and tighten the pores and clog them (something like the 
clogging of a filter). Protein stacked behind these clogged pores gets 
deverted around them and contributes to the "streaks"
.
At lower voltage gradients, the aggrgates have more time to disaggregate 
and reptate through the less tight pores without clogging them.

If you want to get a better feel of how polyacylamide gel 
electrophoresis works, download the Adobe Acrobat version of my original 
1964 paper from:

<http://www.pipeline.com/~lenornst/DiscElectrophoresis.html>  .

Len Ornstein  (of Davis & Ornstein)    

Scott McMahan wrote:
> 
> I was having problems recently with the samples of my Tris-Tricine
> SDS-PAGE/Westerns streaking vertically.  After checking the usual suspects
> (old sample buffer, precipitated sample, etc.)  I found a few protocol
> books mentioning that turning the current down sometimes helps this
> problem.  When I did that, it did drastically decrease the streaking, but
> really increased the running time.  I was wondering if anyone knew what
> phenomenon is causing this streaking, and is there some other way of
> correcting it so I can run my gels faster again.
> 
> --
>                                          Scott McMahan
>                                          mcmahan at oncology.wisc.edu



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