The N-terminal His-tag affects the enantioselectivity of staphylococcal lipases: a monolayer study.

In order to check the influence of the polyhistidine tag at the N-terminus of recombinant lipases, a comparative study on the interfacial properties of native and recombinant Staphylococcus simulans (SSL and rSSL) or Staphylococcus xylosus lipase (SXL and rSXL) was investigated using the monomolecular film technique. No phospholipase activity was detected with rSSL or rSXL when using different phospholipids spread as monomolecular films maintained at various surface pressures, suggesting that the His-tag in the N-terminus of the recombinant proteins, do not affect the substrate recognition. The critical surface pressure measured with monomolecular films of egg-PC was slightly lowered with the two recombinant proteins compared to the native SSL or SXL one. A kinetic study on the surface pressure dependency, stereoselectivity and regioselectivity of native and recombinant SSL or SXL was performed using three dicaprin isomers spread as monomolecular films at the air-water interface. Our results show clearly that the presence of polyhistidine tag at the N-terminus of SSL or SXL changes their stereo- and regioselectivity.