Kinetics of PS decarboxylation by PSD monitored by ζ potential. PSD was added to a final protein concentration of 16 μg/mL to symmetric liposomes consisting of 80 mol % PC and 20 mol % PS with 1 mM total lipid. The assay mixture was incubated at 28°C with slight agitation. Measurements were performed at 28°C, ζ potential was measured in regular time intervals to observe the decarboxylation of PS (green circles). (A) Light and dark gray triangles compare ζ potential before (Ø Ni-PD) and after PSD removal (+Ni-PD), respectively, incubated at 20°C for 4 days. Black triangles show the ζ potential of untreated symmetric liposomes. Error bars indicate the SD of three measurements of the same sample. (B) Repetition of the assay as shown in (A); after 90 min, a second dose of 16-μg/mL PSD is added. To see this figure in color, go online.