IPTG Concentration and E.Coli OD - (Dec/21/2008 )

Can some one tell me what should be the concentation of IPTG for inducation and whats the good OD for the induction.

As first approach i usually use 1.5mM of IPTG and induce culture at O.D.~0.5-0.6. Some people say that 1.5mM of IPTG is too much, i use this because if bacteria don't express protein isn't due to IPTG. But as i said it is just a first try.

Good luck in your work

The right conditions to use are different for every protein you try to express and differ in different cells. I usually start by doing small scale cultures (50 ml) and testing different IPTG concs (0.5, 1 mM), different temps (18, 30, 37C) and different times (2, 4, 6 hours). I usually induce at O.D600 = 0.6 but others in my lab get better expression when they induce at 0.9.

You need to find the best conditions for your protein.