Protein expression and E.coli strain.

Cornelius Krasel krasel at
Mon Jun 2 08:28:20 EST 1997

Chris Kafer (ckafer at wrote:
> I am using the pGex GST fusion system to express my Arabidopsis
> protein. Supposedly it works in any bug though they recommend BL21.  I
> have been using XL1Blue and have yet to see my protein in a gel.  Is
> XL1 Blue an acceptable strain for protein expression?

Yes. BL21 is recommended because it has less proteases. There are,
however, proteins that will not express well or at all in any
E. coli strain, no matter what you try.

It is, however, surprising that you don't get any protein at all. It
might help to give some additional information:

- do you see any GST bands (running at 27 kB)
- do you get inclusion bodies, instead of soluble protein (i.e. did
  you look in your pellet?)


/* Cornelius Krasel, U Wuerzburg, Dept. of Pharmacology, Versbacher Str. 9 */
/* D-97078 Wuerzburg, Germany   email: phak004 at  SP3 */
/* "Science is the game we play with God to find out what His rules are."  */

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