Interaction of N-acyltaurines with phosphatidylcholines

Abstract

N-acyltaurines (NATs) are biologically active amphiphilic lipids. They come under the group of compounds known as N-acyl amino acids. NATs were first detected in the brain and other tissues in mice lacking the enzyme fatty acid amide hydrolase FAAH (−/−). N-arachidonoyltaurine (20:4 NAT) acts as an excellent ligand for the subset of transient receptor potential (TRP) channels, especially vanilloid type channels TRPV1 and TRPV4. Also, hydrophobic and hydrophilic regions of NATs enable them to interact with membrane lipids. Here, we have investigated the interaction of NATs, N-myristoyltaurine (NMT), and N-palmitoyltaurine (NPT) with their corresponding diacyl phosphatidylcholines (PCs), dimyristoylphosphatidylcholine (DMPC), and dipalmitoylphosphatidylchoine (DPPC). The miscibility and phase behavior of the hydrated binary mixtures have been investigated by differential scanning calorimetry (DSC). Studies on the interaction of NMT/NPT with DMPC/DPPC revealed that the two amphiphiles mix well up to 50 mol% of NAT and phase separation is observed at higher contents of the NAT. The phase transition of the equimolar mixtures of NAT:PC (50:50) studied by fluorescence, also supported the DSC results. PXRD and FTIR analysis show that the NAT:PC equimolar mixture (50:50) forms different supramolecular structures when compared to that of individual NATs and PCs. From transmission electron microscopic studies it is observed that the equimolar mixtures of NMT and NPT with their corresponding diacylphosphatidylcholines (50:50, mol/mol) forms unilamellar vesicles whose diameter range between 30 and 50 nm.