Heterologous Expression and Functional Characterization of Sparidae Fish Digestive Phospholipase A2.

In this study, we have produced for the first time a fish phospholipase (PLA(2)) in heterologous system (E. coli). The Diplodus annularis PLA(2) (DaPLA(2)) was then refolded from inclusion bodies and purified by Ni-affinity chromatography. We used the pH-stat method (with emulsified phosphatidylcholine as substrate) and the monomolecular film technique (using various glycerophospholipids substrates spread in the form of monomolecular films at the air-water interface) to access the biochemical and kinetic properties of the recombinant DaPLA(2). The DaPLA(2) was found to be active and stable at higher temperatures (37-50 degrees C) than expected. Interestingly, DaPLA(2) hydrolyzes efficiently both purified phosphatidylglycerol and phosphatidylethanolamine at 20 mN/m. These analytical results corroborate with the fact that the catalytic activity of DaPLA(2), measured with the pH-stat using egg yolk as substrate, is mainly due to the hydrolysis of the PE fraction present in egg yolk, whereas the phosphatidylglycerol is a hallmark substrate for the most secreted PLA(2)-IB.