The Cytoplasmic and Periplasmic Expression Levels and Folding of Organophosphorus Hydrolase Enzyme in Escherichia coli.

BACKGROUND Organophosphorus hydrolase (OPH) is a type of organophosphate-degrading enzyme which is widely used in the bioremediation process. OBJECTIVES In this study, the periplasmic and cytoplasmic productions and the activity of recombinant OPH in Escherichia coli were investigated and compared using two pET systems (pET21a and pET26b). MATERIALS AND METHODS The sequence encoding the opd gene was synthesized and expressed in the form of inclusion body using pET21a-opd and in the periplasmic space in pET26b-opd. RESULTS Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed a band of about 37 kDa with a maximum expression level at 30°C from pET21a-opd.However, the obtained results of the periplasmic space extraction of OPH (pET26b-opd) showed a very weak band, while the cytoplasmic expression of OPH (pET21a-opd) produced a strong protein band. CONCLUSIONS The activities studied by the production of PNP were determined by following the increase at 410 nm. The maximum PNP was produced at 30°C with an optical density of 10.62 in the presence of cytoplasmic expression of OPH (pET21a-opd). Consequently, our results suggest cytoplasmic expression system as an appropriate candidate with a high amount of OPH in spite of inclusion body formation, which needs an additional refolding step.