Dipalmitoylphosphatidylethanolamine

Ahkong QF, Tilcock C. Attachment of Tc to lipid vesicles containing the lipophilic chelate dipalmitoylphosphatidylethanolamine-DTTA. Nucl Med Biol 1992 19 831. 

An interesting phenomenon is noted at the 4 (4 ) positions of both DPPC and dipalmitoylphosphatidylethanolamine (DPPE) in the gel phases. Substantial conformational disorder is observed. The data for the 4-d DPPE are shown in Figure 5. The observation of 6.72 disorder is consistent with the data for 4-d DPPC (Table III) below Tffl. Possible origins of this somewhat unexpected result are suggested below. 

Figure 1 Examples of lipids found commonly and used in cells, (a) DPPC (b) 1-palmitoyl-2-(1-pyrenedecanoyl)-sn-glycero-3-phosphocholine (PyrPC) (c) Palmitoyl-SM (d) Cholesterol (e) Dipalmitoylphosphatidylethanolamine (f) 1,2-di-0-palmitoyl-3-0-fi-D-galactosyl-sn-glycerol (DPGALA). Of these lipids, PyrPC is a pyrene-linked lipid probe and DPGALA is a glycolipid. The first four lipids are represented by a united-atom description, and the last two lipids are represented by a full-atom description.

Not only the analysis of triglycerides can be done using GC/MS. The EI+ mass spectra of other lipids with relatively small molecules are known. As an example, Figure 8.1.2 shows the mass spectrum for dipalmitoylphosphatidylethanolamine in EI+ standard conditions. 

Figure 8.1.2. The mass spectrum (EI+ standard conditions) for dipalmitoylphosphatidylethanolamine.

In a subsequent study, van Hal et al. [40] reported that a decrease in cholesterol content in liquid state bilayers, which increases bilayer fluidity, resulted in an increase in estradiol transport across SC. With confocal laser scanning microscopy, Meuwissen et al. examined the diffusion depth of gel- vs. liquid-state liposomes labeled with fluorescein-dipalmitoylphosphatidylethanolamine (fluorescein-DPPE) with human skin in vitro [41] (Figure 3) and rat skin in vivo [42] and found that the lipophilic label when applied in liquid-state bilayers onto the skin penetrated deeper into the skin than when applied in gel-state liposomes. Recently, Fresta and Puglisi [43] reported that corticosteroid dermal delivery with skin-lipid liposomes was more effective than delivery with phospholipid vesicles, both with respect to higher drug concentrations in deeper skin layers and therapeutic effectiveness. This is a very surprising result, because skin lipid liposomes are rigid and form stacks of lamellae on the surface of the skin [44]. From the previously mentioned studies it seems clear that the thermodynamic state of the bilayer plays a crucial role in the effect of vesicles on dmg transport rate across skin in vitro. 

Thus far, we have aligned the following lipids dilauroyl-, dimyristoyl-, dipalmitoyl-, diphytanoyl-, and dioleoylphosphatidylcholine (DLPC, DMPC, DPPC, DPhPC, and DOPC, respectively), dimyristoylphosphatidylglycerol (DMPG), dipalmitoylphosphatidylethanolamine (DPPE), L-a-phosphati-... 

In a typical experiment, Israelachvili deposited monolayers of surfactants onto cleaved mica sheets, and evaluated the surface energies. For example, mica coated with monolayers of L-a-dipalmitoylphosphatidylethanolamine (DMPE) showed no hysteresis (yx = yR = 27mJ/m, but when coated with hexadeeyltrimethylammonium bromide (CTAB) it was found that yx = 2J0mJ/m and )/R = 50mJ/m. ... 

All films were prepared from solutions in chloroform/methanol (2 1, v/v), except for dipalmitoylphosphatidylethanolamine films which were prepared from a chloroform solution. DPPC, dipalmitoylphosphatidylcholine DLPC, dilauroylphosphatidylcholine DPPE, dipalmitoylphosphatidylethanolamine s, shoulder. 

Dipalmitoyl-5/i-glyccro-L-serine, in G-00045 Dipalmitoylphosphatidic acid, see G-00040 Dipalmitoylphosphatidylcarnitine, D-00175 Dipalmitoylphosphatidylcholine, see G-00041 Dipalmitoylphosphatidylethanolamine, see... 

On the other hand, the present lipids have different chain lengths. This is because when the dimyristoylphosphatidylcholine (DMPC) system is used in place of the DPPC system, its subgel phase exists at temperatures below at least 0°C (i.e., it is impossible to measure the ice-melting curve for the subgel phase). Similarly, when the dipalmitoylphosphatidylethanolamine (DPPE) system is used in place of the DMPE system, the system requires much longer periods (at least 40 days) for completion of the conversion of the gel to the subgel phase by annealing. 

The structural model sketched in Figure 6 was based [28, 29] on the electron density profile and the available knowledge of the lipid, dipalmitoylphosphatidylethanolamine (DPPE) and of the surface layer protein from B. sphaericus CCM2177. 

Dinitrophenyl dipalmitoylphosphatidylethanolamine (DNP-DPPE) is well known for its potential as an antigen in the preparation of immunologically responsive liposomal model [1, 2]. It has been found that this compound was capable of actively sensitizing liposomes toward antibody complement. However, the physicochemical properties of the membrane of DNP-DPPE, especially those of the monolayer at an air/water interface, are not yet clear. As the dinitrophenyl group plays an important role in some immunological reactions, the interaction... 

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