Expression and non-chromatographic purification of 1,3-propanediol oxidoreductase in Escherichia coli
The gene dhaT from Klebsiella pneumoniae encodes 1,3-propanediol oxidoreductase (PDOR). Thermally responsive elastin-like polypeptides (ELPs) was used as a fusion tag to purify the proteins (PDOR). The ELP gene was attached to dhaT and ligated into the pET-22b vector. Different NaCl concentrations were employed to decrease the transition temperature (Tt) which was diminished as salt concentration increased. The optimal final concentration of NaCl was 1 M and the corresponding Tt was 39.5ºC. Enzymatic assays were determined via every step for purification of fusion PDOR. PDOR showed good stability during the purification process, the specific activity in the first and second round of inverse transition cycling (ITC) was 276.1 ± 13.3 and 213.3 ± 10.8 U/mg, respectively. The ELPs fusion PDOR was superior to histidine tagged PDOR in both yield and activity after the purification.