Hi Nadia, it depends on the vector you are using for expression. A multitude of vectors for recombinant expression in bacteria has a T7 promoter, which means that your target gene is transcribed by a T7 RNA polymerase. For this, you have to use a bacterial strain that has the gene for the T7 RNA polymerase, which would be BL21(DE3) in your list (or every other strain marked as DE3).
Other vectors may use different promoters like T5, which can be recognized by virtually every RNA polymerase (I guess...). So JM109 could work as well in this case. DH5alpha aren't suitable (at least not for high level expression), because they are engineered for cloning purposes and plasmid propagation. Refer to the handbook of your cloning vector if you are not sure what kind of promoter your plasmid has. They often contain many other useful hints for optimizing protein expression. Good luck! T -- GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT! Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01 _______________________________________________ Methods mailing list Methods@net.bio.net http://www.bio.net/biomail/listinfo/methods
