pET and ampicillin

Craig A. Altier caa3 at po.CWRU.Edu
Tue Nov 22 17:07:30 EST 1994

In a previous article, rbrooksb at (Dr. R.A. Brooksbank) says:

>I found that clavulanic acid did seem to help when expressing proteins in
>E.coli. I too found that with ampicillin the pET vector construct was lost 
>from the culture. I used Timentin, this is a mixture of clavulanic acid and an
>ampicillin analogue (sorry I don't have the info on what!). Timentin is a
>propriatry name made by Smith Kline Beecham (if my memory serves me well). A
>point to be aware of is the fact that it is very hard to start a culture in
>the presence of Timentin, I grew starter culture to a very low density (barely
>visible turbidity) using ampicillin and then used these to innoculate a larger
>culture containing the timentin. Can't promise it will work for you but good 
>Rob Brooksbank        rab at
>The Sanger Centre, Hinxton Hall, Cambridge

	Timentin is a 30:1 combination of ticarcillin and clavulanic acid.
The protein-junkies in our lab (I'm not one of them) use it in various ways.
One uses it with a very unstable plasmid at 80ug/ml along with ampicillin at 
25ug/ml.  This maintains his plasmid, but gives extremely slow growth.  He
says that he has grown the starter culture with ampicillin with or without
Timentin and both will grow (although with Timentin it grows much more slowly).
Another person in the lab uses it without any added amp at 16ug/ml.  So, it 
looks like there is a fairly wide range of useful concentrations (or perhaps
it is just personal preference).

Craig Altier

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