Protein Expression

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aabera's picture
Protein Expression

I was trying to express recombinant protein in e_coli.  I added 15ml of over night cells to each 1 L LB/Amp which is an SOP for this project.  When I monitor the growth to induce with IPTG, the 1L showed the usual growth speed where as the other one was very slow.  I decided to induce the normal growth with IPTG and left the other one with out induction.  The next morning, I did expression test on SDS-page.  Even though both of them showed the intended protein band, the one with out IPTG showed high level of expression.  Does it mean that my protein was expressed  with out IPTG? Could protein be expressed with out IPTG? If so what is thatnmean to my recombinant protein.  What would be the best way to avoid this kind of faulty expression from happening?

Ashenafi Abera
Univeristy of Alberta

raviuic's picture
Yes, the proetein can also be

Yes, the proetein can also be expressed without IPTG, if the promoter is not tightly regulated by an inducer.

Rajeshwari patel
Rajeshwari patel's picture
   Yes protein can also be

   Yes protein can also be xpressed with out IPTG If  prmotor is leaky as well as there are lactose present in the media, First you check wether lactose contamination with your medaior not?