Fig. 2

Purification and identification of AK2. a Analysis of expression and purification of AK2 using 12% SDS-PAGE. Lane 1: Protein molecular weight standard; Lane 2: Lysate of E. coli AK2/HB2151 not induced with IPTG; Lane 3: Lysate of E.coli AK2/HB2151 induced by IPTG; Lane 4: Crude proteins adsorbed to Ni²⁺-NTA column; Lane 5: Flowthroughs of crude protein sample from Ni²⁺-NTA column; Lane 6: Washes from Ni²⁺-NTA column with binding buffer; Lane 7: Washes from Ni²⁺-NTA column with washing buffer; Lane 8: Elution from Ni²⁺-NTA column with elution buffer. b Western blot analysis of purified AK2 using anti-V5 tag monoclonal antibody and anti-His tag monoclonal antibody probes, respectively. Lanes 1 and 2: Cell lysate of E. coli AK2/HB2151 induced without or with IPTG, respectively; Lane 3: Culture supernatant of E. coli AK2/HB2151 induced by IPTG; Lane 4: Purified AK2 protein. The original blot image is shown in Additional file 1: Fig S2. c, d Recognition of purified AK2 by ELISA. Purified AK2 was coated onto the microtiter plates to conduct ELISA using anti-His tag monoclonal antibody (c) and anti-V5 tag monoclonal antibody (d). Wells coated with BSA served as the negative control (NC)