Phosphatidate structure

A, the structure of phosphatidic acid. H of this structure is replaced by grouping B-D to give the following phospholipids ... 

Figure 12.11 Phosphoglyceride structure. The members of this group are derivatives of the parent compound, l,2-diacyl-src-glycerol-3-phosphate (phosphatidic acid) in which X is a hydrogen atom. This is replaced by either an amino alcohol or a polyhydroxy residue. In phosphoglycerides derived from animal tissues R1 is usually a saturated acyl chain of between 16 and 20 carbon atoms and R2 is usually unsaturated. Polyunsaturated acyl chains containing 16 or 18 carbon atoms predominate in leaf phosphoglycerides and those of bacterial origin are often more complex.

The simplest of the glycerophospholipids is phosphatidic acid, in which phosphate is linked to the third hydroxyl function, forming a phosphate ester. More complex glycerophospholipids are derivatives of phosphatidic acid in which one of several groups is attached commonly choline, ethanolamine, serine, or myo-inositol. Structures are collected in table 19.1. 

Phosphatidic acid the structural backbone of the glycerophospholipids two molecules of fatty acids are esterified to a molecule of glyceryl phosphate. 

Figure 4-1. Structures of the membrane bilayer and an amphipathic phospholipid. The head group attachment, X, may be H as in phosphatidic acid or one of several substituents linked via phosphoesters in the glycerophospholipids. The nonpolar tail is depicted as composed of saturated fatty acids in this molecule. The overall length of the hydrocarbon chain of the fatty acids may vary from 14 to 20.

A. Structures of some glycerophospholipids. B. Phosphatidic acid. = phosphate, PO4-2. 

Structure and function of cardiolipin Cardiolipin contains two molecules of phosphatidic acid esterified through their phosphate groups to an additional molecule of glycerol. This is the only human glycerophospholipid that is antigenic. It is an important component of the inner mitochondrial membrane. 

Structure of phosphatidic acid, a phosphoglyceride. A saturated fatty acid is esterified at carbon 1 of the glycerol, and a cA-unsaturated fatty acid at carbon 2. The cluster of polar and charged oxygens makes the head-group hydrophilic, in marked contrast to the hydrophobic fatty acid chains. 

Lipid synthesis is unique in that it is almost exclusively localized to the surface of membrane structures. The reason for this restriction is the amphipathic nature of the lipid molecules. Phospholipids are biosynthesized by acylation of either glycerol-3-phosphate or dihydroxyacetone phosphate to form phosphatidic acid. This central intermediate can be converted into phospholipids by two different pathways. In one of these, phosphatidic acid reacts with CTP to yield CDP-diacylglycerol, which in bacteria is converted to phosphatidylserine, phosphatidylglycerol, or diphos-... 

Figure 8.1. The structure of some common phospholipids ( ) phosphatidylcholine, (b) phosphatidylethanolamine and (c) phosphatidic acid.

Fig. 25 (a) DNA release from EDOPC-DNA lipoplexes after addition of negatively charged lipid dispersion, as monitored by FRET (CM, oleic acid DOPA, dioleoyl phosphatidic acid DOPG, dioleoyl phosphatidylglycerol CL, cardiolipin DOPS, dioleoyl phosphatidylserine PI, phospha-tidylinositol). (b) Fraction of released DNA from EDOPC lipoplexes 10 min after addition of the respective anionic liposomes (c) X-ray diffraction patterns of mixtures of EDOPC and anionic liposome dispersions the respective structures are shown schematically on the left side (reproduced with permission from [98] copyright (2004) Biophysical Society)... 

The simplest type of phosphoinositide is represented by the phosphatide isolated from horse liver or dog liver by McKibbin.171 This consists only of glycerol, myo-inositol, phosphoric acid, and fatty acids it probably has structure LXXX. Similar inositides, differing only in the nature of the fatty acids, have been isolated from wheat germ,187 beef heart, 188 and beef liver.189 That the major portion of the fatty acids is attached to glycerol, not to myo-inositol, was shown by the isolation of a diglyceride on mild hydrolysis.189... 

The phosphatidic acids could potentially be found as a mixture of the 1-0-diacyl-, alkylacyl-, and alkenylacylglycerophosphoric acids. Structural characterization follows almost exactly the route as described for the lysophosphatidic acids. 

---