expressed protein is 5-6kda bigger than

[Wulf Dirk Leuschner]

imazhq at leonis.nus.sg (Zheng Huanquan) wrote:

>Does anyone have such experience that expressed protein is 5-6kda bigger 
>that native one? my protein is 33kda and has additional 13aa + 6x His, 
>thus the expressed protein should 35-36kda, but I only got 40-42kda 
>expressed. Any explain? 

>thank you!

>Hugo Zheng

Hi Hugo,

it depends in what kind of organism you have the protein expressed. If
it is, e.g., in mammalian cells, glycosylation might be the problem. 
Sometimes proteins have 'abnormal' mobilities in SDS-PAGE (although
their  molecular weight is correct) due to some conformation (even
with SDS!) which influences the migration properties of the protein.

WDL