Constitutive Fusion Protein Expression in BL21(DE3) Cells

[Zophonias O. Jonsson]

In article <biotech-0403961716060001 at cyto.cytosignal.com>, biotech at ni.net
(David J Benz) wrote:

[snip!]

> But I think we have a more fundamental problem. I think our bacteria are
> changing somehow so that expression becomes constitutive. 

[snip!]

> David

There is a very easy way to test you hypothesis.  Get some fresh BL21(DE3)
cells and compare to the ones you are using.  If it is really important
that there is no leakage expression I would recommend pLysS or pLysE
strains, but to me it would seem that you could turn the constitutive
expression to your advantage.  You could grow the bugs slowly (e.g. at low
temp) and thus giving the expressed protein a better chance of folding
correctly.

Zophonias

_____________________________________________________________________
Zophonias O. Jonsson
Institut fur Veterinarbiochemie               Tel: (41-1)-257-54-75
Universitat Zurich-Irchel                     Fax: (41-1)-362-05-01
Winterthurerstrasse 190
CH-8057 Zurich
Switzerland
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