Check to see if it is glycosylated. There are stains (like stains-all) that
will show if a polypeptide is conjugated. Glycosylation will cause it migrate
Quoting Mehmet Sen <senmehmetsen at yahoo.com>:
> It happen to me too. My protein is 26 kDa, and walking in the SDS-PAGE
> as 31 kDa protein, it is very interesting. any reason for that? may be
> even in the denatured form, it takes sort of folding which gives rise
> to bigger radius to protein than what we expect as a radius of
> protein, it is getting slow down. I am not really sure, this is my
> Mehmet Sen
>>>miaoqf at sina.com wrote in message
> news:<20040209144331.31153.qmail at ww02.hostica.com>...
> > I expressed a protein in E.coli sucessfully and the DNA sequence is right.
> The theoretical MW is 25KD. But after its purification, the MW is 29-30KD in
> a reducing-SDS PAGE. More surprised me is the MW is 25KD when I run it in a
> non-reducing SDS pAGE. I don't know the reason. Who can help me ?
Hiranya S. Roychowdhury, Ph.D.
Coll. Asst. Professor,
Dept. of Chemistry & Biochemistry
Rm# 336, Chemistry Bldg.; MSC 3MLS
New Mexico State University
Las Cruces, NM 88003