Fig. 3

Expression and purification of secreted Nat-Csn and OmpA-Csn from culture supernatant. SDS-PAGE analysis of constructs containing native (a) or OmpA (b) signal peptides from culture supernatant (left panel) and cell lysate (right panel) at various purification steps are shown. Equal volumes (15 µL/lane) of samples were loaded into lanes, except for crude lysate, of which 5 µL/lane was loaded. c The comparison of crude enzymes obtained from culture broth after 20 h of induction with 0.1 mM IPTG. Equal volumes of culture broth (15 µL/lane) were loaded into each lane. Purified proteins from culture broth were separated by SDS-PAGE on 15 % gels and transferred onto PVDF membrane for N-terminal amino acid sequencing (d)