Langmuir, Vol.16, No.21, 8010-8015, 2000
Design and synthesis of phosphatidylcholine mimics and their mixing behavior with phosphatidylglycerol mimics in the fluid bilayer state
Two disulfide-based phospholipid dimers have been synthesized ((PCPC14)-P-14 and (PCPC16)-P-16), which have packing behavior, melting temperatures, and monomer unit structures that mimic those of I,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). Examination of the mixing behavior of pC(16) and analogous phosphatidylglycerol (PG) mimic, by use of the nearest-neighbor recognition method, has revealed that these Lipids are ideally miscible in the physiologically relevant fluid phase. Addition of a hydrocarbon chain length mismatch of four methylenes per acyl chain and/or the addition of 29 mol % cholesterol do not alter such miscibility. In contrast, the inclusion of a basic peptide (pentalysine) affords a modest degree of nearest-neighbor recognition. The introduction of exchangeable phospholipid dimers that mimic phosphatidylcholines significantly expands the scope of the nearest-neighbor recognition method and increases its relevance to the study of animal cell membranes, whose two-dimensional structures remain to be elucidated.