Effect of negatively charged lipid on LPLA2 activity. The reaction mixture contained 48 mM sodium citrate (pH 4.5), 10 μg/ml BSA, liposomes (127 μM phospholipid), and 14.5 ng/ml of recombinant mouse LPLA2 in 500 μl of total volume. A: Liposomes consisting of DOPC-NAS (3:1, molar ratio) or DOP-sulfatide-NAS (3:0.3:1, molar ratio) were incubated with the enzyme for 5, 10, 15, 30, and 45 min at 37°C. The reaction products were extracted and separated by an HPTLC plate using a solvent system consisting of chloroform-acetic acid (9:1, v/v). The reaction product, 1-O-oleoyl-NAS, quantified by scanning the plate, was plotted against time (B). C: Liposomes consisting of DOPC-galactosylceramide-NAS or DOPC-sulfatide-NAS with a different molar ratio were incubated with the recombinant enzyme at 37°C. The reaction products were extracted and separated as described in A. Error bars indicate SD. (n = 3).