1-palmitoyl-2-oleoylphosphatidylethanolamine--(z-&-r)-isomer and dioleoyl-phosphatidylethanolamine

Because transmembrane proteins (TMPs) can be obtained with sufficient purity for X-ray diffraction studies more frequently than decades ago, their mechanisms of action may now be elucidated. One of the pending issues is the actual interplay between transmembrane proteins and membrane lipids. There is strong evidence of the involvement of specific lipids with some membrane proteins, such as the potassium crystallographically sited activation channel (KcsA) of Streptomyces lividans and the secondary transporter of lactose LacY of Escherichia coli, the activities of which are associated with the presence of anionic phospholipids such as the phosphatidylglycerol (PG) and phosphatidyethanolamine (PE), respectively. Other proteins such as the large conductance mechanosensitive channel (MscL) of E. coli seem to depend on the adaptation of specific phospholipids to the irregular surface of the integral membrane protein. In this work we investigated the lateral compressibility of two homoacid phosphatidylethanolamines (one with both acyl chains unsaturated (DOPE), the other with the acyl chains saturated (DPPE)) and the heteroacid phosphatidyletanolamine (POPE) and their mixtures with POPG. The liquid expanded (LE) to liquid condensed (LC) transition was observed in POPE at a temperature below its critical temperature (T

Topics: Bacterial Proteins; Compressive Strength; Escherichia coli; Escherichia coli Proteins; Ion Channels; Microscopy, Atomic Force; Monosaccharide Transport Proteins; Phosphatidylethanolamines; Potassium Channels; Streptomyces lividans; Symporters; Temperature; Thermodynamics; Unilamellar Liposomes