Recombinase Cre's overexpression in Escherichia coli BL21(DE3) and its one-step purification and activity assay

In order to realize the application of Cre recombinase in vitro,plasmid pTE30-Cre was constructed based on a pET-30a vector.This plasmid was transferred into Escherichia coli BL21(DE3).The Cre gene was overexpressed and then induced by IPTG.The Cre recombinase protein was easily purified using a Ni⁺ affinity column and its activity was tested in vitro by providing a plasmid which contained two of the same directional loxP sites.