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T7 and T7lac
1 reply to this topic
Posted 02 May 2009 - 05:10 AM
Can anyone tell me the difference between T7 and T7lac?
T7lac contains a lac operator sequence downstream of the T7 promotor.
In the presence of the lac repressor protein (supplied either by the E.coli strain or encoded on the expression plasmid) this minimizes background expression. This is the low level of protein production that occurs before induction.
If your recombinant protein is highly toxic to BL21(DE3) hosts, using the T7lac promotor/operator will significantly increase your chances of a successful expression.
If you are unfamiliar with the structure and function of the "lac operon" a glance in any biochemistry text book will help.