Phosphatidylcholine chemical structure

Figure 1 Chemical structure and space-filling representation of a phosphatidylcholine, DPPC. Different parts of the molecule are referred to by the labels at the left together the choline and phosphate are referred to as the headgroup, which is zwitteriomc. In the space-filling model, H atoms are white, O and P gray, and C black. (From Ref. 55.)...

The different phosphoglycerides are often named by placing the constituent attached to the phosphate group after phosphatidyl , e.g. phosphatidyl choline (3-in-phosphatidylcholine or l,2-diacyl-sn-glycero-3-phosphoryl-choline). There are many phosphoglycerides because of the possible variation in the fatty acid chains, and when the full chemical structure is known, it should be used (e.g. l-palmitoyl-2-oleoyl-phosphatidylcholine). Nomenclature that entails the use of the DL system should be avoided. 

Fig I. Chemical structure nf phosphatidylcholine (PC) (I) and other related phospholipids. o represents falls acid residues. The choline frag-... 

Fig. 2 Chemical structures of the zwitterionic neutral lipids DOPC (1,2-dioleoyl-.s -glycero-3-phosphatidylcholine) and DOPE (l,2-dioleoyl-S7J-glycero-3-phosphatidylethanolamine) and the cationic lipids DOTAP (l,2-dioleoyl-3-trimethylammonium-propane, a UVL) and MVL5 (a custom-synthesized MVL)...

Figure 4.6.2 The chemical structure of a dipalmitoyl phosphatidylcholine (DPPC) amphiphatic lipid and its organization in model membranes...

MTD was incorporated preferentially into triacylglycerols rather than into phospholipids. The proportion of 13-MTD in both phospholipids and triacylglycerols increased to saturation level in 6 h of incubation. The metabolic fate of fatty acids thus showed diversity with their chemical structures and resulted in uneven positional distribution in triacylglycerol or phospholipid molecules [35], Triacylglycerols contained almost equal proportions of 13-MTD at the sn-2 position and at the sn-1,3 positions. 13-MTD was incorporated into phosphatidylcholine to a greater extent than into phosphatidylethanolamine, with preference for the sn-2 position. 

FIGURE 10.1 Chemical structures of typical OxPCs generated by peroxidation of paknitoyl-arachidonoyl-phosphatidylcholine. The figure presents a few most common molecular species selected from dozens of molecular species produced by nonenzymatic oxidation of a single precursor phospholipid. Note that oxidation can either add oxy functions to the full-size carbon chain or induce chain fragmentation. Both types of modifications produce phospholipids with abnormal properties and biological activities that were not characteristic of unoxidized phospholipid precursors. 

Fig. 2. Chemical structures of a typical phospholipid (phosphatidylcholine), a glycolipid (galactocerebroside), and two vesicle-forming block copolymers, poly(butadiene-6-ethylene oxide) and poly(styrene-6-acrylic acid.) The grey region indicates the hydrophobic interior of the bilayer.

Figure 5 Chemical structure of Ghadiri s cyclic peptide 18 which undergoes self-association in phosphatidylcholine liposomes to form nanotubes that transport glucose across the membrane.

These questions also have a chemical component it would be helpful to understand the relationship between the chemical structure of the monomeric surfactant and the propensity to assemble to giant vesicles. It has been observed that, generally, a small amount of giant vesicles accompanies the formation of normal vesicles. However, this tendency varies strongly from surfactant to surfactant. This situation also occurs in the case of electroformation [2] some surfactants (e.g. fatty acids/soaps, phosphatidyl nucleosides) fail to give giant vesicles by the electro-formation method [3], and in fact the method seems to be restricted to phosphatidylcholine or to lipid mixtures containing phosphatidylcholine. It is fair to say that the relationship between the chemical structure and the propensity to form vesicles is still poorly understood. 

The results show that vesicle formation by electroformation for pure lipids other than POPC (or other phosphatidylcholines) is difficult. Vesicles can only form when the lipids are mixed with POPC. It seems that small changes in the chemical structure of the lipid strongly influence the lipid swelling in the electric field and the whole electroosmosis-supported formation process. 

Glycerol containing phospholipids are used for the preparation of liposomes and vesicles phosphatidylcholine - phosphatidylserine - phosphatidylethanolamine -phosphatidylanisitol - phosphatidylglycerol - phosphatidic acid - cholesterol. The chemical structure of some of these lipids was given before. In most preparations, a mixture of lipids is used to obtain the most optimum structure. 

In the direct chemical attack for proof of structure of phosphatidylcholine (see the section entitled Glycerophosphochline Characterization ) the decision was made to subject this phospholipid to a base-catalyzed methanolysis. As noted, two products are formed, namely, glycerophosphocholine and the methyl esters of the long-chain fatty acid substituents on the intact phosphatidylcholine. Since the analytical approach to proof of structure of the glycerophosphocholine has been achieved, it is logical now to consider the other product, the methyl esters. 

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