Recombinant Smek CatB (rSmek CatB) was obtained by lysing bacteria cells with the lysis buffer (50 mM NaH2PO4, 300 mM NaCl, 8 M urea, 6 MGnHCl and 20 mM Immidazole pH 8.0), and the protein was puri-fied by binding to 1 ml of Ni-NTA Agarose resin (Qiagen, Germany)in a 15 ml column, washed with washing buffer containing 20 mMImidazole and eluted from the resin with elution buffer containing250 mM Imidazole.