Imidazole Headgroup Phospholipid Shows Asymmetric Distribution in Vesicles and Zinc-Dependent Esterase Activity

Artificial lipids have become increasingly important in generating novel nanoenzymes and nanoparticles. Imidazole has been well established as a versatile catalyst in synthetic chemistry and through its related amino acid histidine in enzymes. By exploiting the transphosphatidylation reaction of phospholipase D, the choline headgroup of phosphatidyl choline was exchanged for the imidazole moiety containing histidinol. Here, we introduce a novel phosphatidylhistidinol (PtdHisOH) lipid and characterise it with respect to its catalytic abilities and its ability to modulate vesicle size. Our data reveal a zinc-dependent esterase activity that was strongest in vesicles and micelles, with slower catalytic rates being observed in flat lipid presentation systems and two-phase systems, indicating the importance of surface presentation and curvature effects on the catalytic activity of PtdHisOH. Such lipids offer the opportunity to impart de novo catalytic functionality to self-assembled lipid systems such as synthetic cells, leading to the development of new technologies for biocatalysis applications.