SDS-PAGE of Serum Sample

Nick Theodorakis nicholas_theodorakis at
Fri Jan 25 09:46:36 EST 2002

Florence <wythum at> wrote in message news:<20020125072945.4044.qmail at>...
> Dear All,
> I'm running SDS-PAGE with serum samples, but I'm having a serious problem
> that there's always a clump of unknown protein aggregates between 98-50 kD,
> and the lanes become twisted.  I've tried to reduce total protein mass to 50
> ug, or purify protein from serum sample using TCA precipitation, but still
> can't solve this problem.

Unknown protein? Do you mean albumin, a 66kDa protein that composes
about half the protein content of serum?

Also make sure you have enough SDS to solubilize all your protein; a
rule of thumb is that you should have at least two times as much SDS
(by weight) as protein, so your 50 ug sample should have more than 100
ug SDS.

BTW, that 50 ug sample should have a 20-25 ug bolus of albumin running
in the 60-70kDa range, so it's no suprise that it would distort the
lane. There are some tricks to removing albumin, which may or may not
work depending on whether they will also remove your protein of


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