IPTG concentration for induction?

[Richard P. Grant]

deusebe at wotan.ens.fr (Danièle EUSEBE) writes:
>    I have to induce beta-galactosidase in a liquid culture of E.coli Y1089
> lysogen for a lambda gt11 phage containing a beta-galactosidase-fusion
> protein gene.
>    I have read in a protocole to use 10 mM IPTG, which seems to me an
> enormous amount, since I have to make a liter scale culture.

Routinely we use 0.1 mM for the modified promoter (Tac?) in pGEX, 
but you should titrate for your application.  This is a general rule - always 
titrate on a small scale when you do something new.

>    Is this concentration required? What is the minimal efficient
> concentration to fully induce beta-galactosidase synthesis?
> 

Isn't b-gal promoter heat-shockable, anyway?

Richard
> 
-- 
Richard P. Grant MA DPhil      rpgrant at molbiol.ox.ac.uk
Nuffield Department of Obstetrics and Gynaecology, University of Oxford.
http://users.ox.ac.uk/~lady0266
No wonder I can't go to parties anymore.