The exchange of DNA between bacteria and helps them to evolve and adapt quickly to changing environment, but also constitutes a serious health problem since the same mechanism for transferring genes for resistance to antibiotics. In the case of transfer of resistance by bacterial conjugation, the protein that initiates the transfer of DNA (relaxase) is key to the process. Conjugative processing of DNA, makes a cut relaxase-specific site (nic site) in plasmid DNA transfer, being covalently bound to the 5 ‘end of nic site. Based on this cut, a mechanism of rolling circle replication produces DNA chain that is transferred to the cell container, while a second transesterification reaction, also catalyzed by relaxase, recircularize plasmid .