why would a recombinant protein increases its molecular weight without treated?

[bjx91250]

hi,
i'm puzzled!
the recombinant protein just fit its molecular weight after affinity purification, but after ion-exchang chromatography, another bigger bands appears accompanied with the weakened former one.

[kmunson779]

Perhaps it's concentration-driven multimerization of the protein. My lab has historically worked with a protein that trimerizes, and this trimerization can be induced by purifying and concentrating it. Once trimerized, it can run as a multimer in SDS-PAGE. See, for example, [Only registered users see links. ], figure 2.

[admin]

Hi Bjx, welcome to the forums
how much bigger is the size of the bands? Could be as Kmunson said aggregates of protein, post-translational modifications such as glycosylation, etc.

Where did you express the protein in Bacteria or Yeast?

[bjx91250]

my protein was expressed in bacteria(Rosseta),and it isn't an oligomer.Mass weighter just shifts about 6kd from 58 to 64 and 52 respectively,at the time being,the theory MW reduced when upons and downs are increasing.thanks you for giving me interpret,look forward to you information!