Interplay of Phospholipase A2 with S-Layer-Supported Lipid Monolayers

Abstract

The present study reports on the enzymatic interplay of porcine pancreatic phospholipase A2 (PLA2) on a monolayer composed of dimyristoylphosphatidylethanolamine (DMPE) in the absence and presence of a recrystallized monomolecular layer of the bacterial cell surface (S-layer) protein SbpA. The PLA2-induced hydrolysis of plain and SbpA-supported DMPE monolayers was monitored by the decay of the surface pressure Π. The same duration of the lag period was observed with SbpA-supported and the corresponding plain DMPE monolayer. The results indicate that the isoporous S-layer protein lattice represents no barrier for the PLA2 diffusing from the bulk to the monolayer surface. This supposition was also confirmed by size exclusion experiments. Most important, the recrystallization of SbpA does not induce defects in the DMPE monolayer from which the PLA2 can benefit. With an S-layer-supported DMPE monolayer, a drop in Π was also observed, but since there are two contributions to Π (SbpA and DMPE monolayer), this p...