cannot find the expression protein - (Jun/19/2008 )

i am trying to express a protein 34kda with his tag in pet20 vector, T7, BL21, in LB medium, i used 1mM IPTG, carbenicillin, incubate the cells at 37C, 6hs, what i got is a protein 116kda. i dont know what is this protein. i repeated the whole process still the huge 116kda protein is the only product.
i have checked the sequence, any suggestions?
i think the IPTG should be fine, cause at least there is another protein expressed. but i tried several times i still cannot find my protein. i didnt use the westenblot or enzyme assay , i think i should at least see some bands on SDS-page of my protein , but there is nothing.

thanks in advance

first of all, is your gene fragment in pET vector the good orientation (reading frame)?
if the first question is OK, check where its stop codon is? is it end of the your gene?
you can use some web based methods to check it.

Hi

commasie cant indicate of ur protein if u cant see it. Induction with IPTG also induce some proteins of the

bacteria like heat shock proteins, so it probably not ur protein.

the absolute way to validate ur induction is by western. dont be lazy, JUST DO IT.