Long-range tilt orientational order in phospholipid monolayers: a comparative study

Abstract

Monolayers of dipalmitoyl-phosphatidyl-N-monomethylethanolamine (DPP(Me)E) and dipalmitoyl-phosphatidyl-N,N-dimethylethanolamine (DPP(Me2)E) are studied and compared with dipalmitoyl-phosphatidylethanolamine (DPPE), dimyristoyl-phosphatidylethanolamine (DMPE), and dipalmitoyl-phosphatidylcholine (DPPC) to characterize the influence of the headgroup size. The properties of the condensed phases of DPP(Me2)E and DPP(Me)E are between those of DPPC and DMPE or DPPE. DPPC domains are elongated and the orientation changes continuously, whereas DMPE domains are compact and the orientation jumps at curved lines. The domains of DPP(Me2)E and DPP(Me)E are compact, and not elongated. The orientation changes continuously by 360 degrees around a point in the centered domains, and jumps of the orientation occur only in the case of twinning. Furthermore, the size of the headgroup influences the erection of the aliphatic chains. For DPPC and (DPP(Me2)E), no complete erection of chains occurs, whereas for DPP(Me)E the surface pressure required for the complete erection of chains is much higher than for DPPE. The same tendency is found for the collapse. DPPC monolayers do not collapse. DPP(Me2)E monolayers collapse at a much higher surface pressure than those of DPP(Me)E and DPPE.

A Theoretical Model of Pulmonary Surfactant Multilayer Collapse under Oscillating Area Conditions

“…This is consistent with experimental evidence that the amphiphilic molecules become more upright during compression (24,25).…”

Effects of Hofmeister Anions on DPPC Langmuir Monolayers at the Air−Water Interface

“…20 The morphology (size and shape) of DPPC monolayer domains in particular has been thoroughly studied over the past 20 years with fluorescence [17][18][19][20] and Brewster angle microscopy. 21,22,[47][48][49] We have obtained BAM images of DPPC monolayers on subphases containing sodium salts of various anions with concentrations ranging between 0.1 and 1.5 M. An image of a DPPC monolayer on a pure water subphase at the same area per lipid is also added for comparison. Although some differences between various electrolytes can be discerned, the overall impression from Figure 4 is that the shapes of the domains are not very sensitive to the specific salt in the subphase.…”

Progress in characterization of Langmuir monolayers by consideration of compressibility

“…This is demonstrated, for example, by a systematic alteration of the head group structure in four monoglycerol amphiphiles by an amide, ether, ester and amine group [8], by four phospholipids of the same chain length which are different only with respect to the number of methyl groups at the nitrogen of the head group [9] or by fatty acids with slightly changed OH-substitution in the mid-positions of the alkyl chain [10,11]. The high sensitivity of the morphological features of the condensed phase domains to the specific stereochemistry has been used for chiral discrimination effects.…”