Streaking of SDS-PAGE samples:Mechanisms

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


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:

<>  .

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

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