Choline glycerophospholipid

Guo, L., Ogamo, A., Ou, Z. et al. (1995) Preferential formation of the hydroperoxide of linoleic acid in choline glycerophospholipids in human erythrocytes membrane during peroxidation with an azo initiator. Free Rad. Biol Med., 18, 1003-12. 

TAG (i.e., fats or oils)), and steroids. These nonpolar lipids are generally soluble in very nonpolar solvents such as hexane, ether, and ester. The polar lipids usually contain a polar head group, such as phosphocholine in choline glycerophospholipids (PC) (see the following), and are usually soluble in relatively polar solvents, such as alcohol, and even water. 

Han, X., Chen, X., Gross, R.W. (1991) Chemical and magnetic inequivalence of glycerol protons in individual subclasses of choline glycerophospholipids implications for subclass-specific cfianges in membrane conformational states. J. Am. Chem. Soc. 113, 7104-7109. 

NLS neutral loss scan or scanning NMR nuclear magnetic resonance OPDA oxo-phytodienoic acid PA phosphatidic acid PC choline glycerophospholipid(s)... 

Plasmalogens are ether glycerophospholipids in which the alkyl moiety is d5-a,/3-unsaturated (Figure 8.10). Common plasmalogen head groups include choline, ethanolamine, and serine. These lipids are referred to as phosphati-dal choline, phosphatidal ethanolamine, and phosphatidal serine. 

Glycerophospholipids are used for membrane synthesis and for producing a hydrophilic surface layer on lipoproteins such as VLDL. In cell membranes, they also serve as a reservoir of second messengers such as diacylglycerol, inositol 1,4,5-triphosphate, and arachidonic acid. Their structure is similar to triglycerides, except that the last fatty acid is replaced by phosphate and a water-soluble group such as choline (phosphatidylcholine, lecithin) or inositol (phosphatidyl-inositol). 

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. 

Figure 5.1 The structure of a glycerophospholipid. A simple diagram showing the charges on the head group. In this struction, palmitic and oleic acids, provide the hydrophobic component of the phospholipids and choline (and four bases) and the phosphate group provide the hydrophilic head. The unsaturated fatty acid, oleic acid, provides a kink in the structure and therefore some flexibility in the membrane structure which allows for fluidity. The more unsaturated the fatty acid, the larger is the kink and hence more fluidity in the membrane. Cholesterol molecules can fill the gaps left by the kink and hence reduce flexibility. Hydroxyl groups on the bases marked are those that form phosphoester links. Choline and inositol may sometimes be deficient in the diet so that they are, possibly, essential micronutrients (Chapter 15).

Definition and example of a glycerophospho-lipid Phospholipids that contain glycerol are called glycerophospholipids or phosphoglyc-erides. All contain phosphatidic acid, the simplest glycerophospholipid. When an alcohol, such as choline, is esterified to phosphatidic acid, the product is phosphatidylcholine. 

Cephalins are glycerophospholipids present in foods. They differ from lecithins by having ethanolamine or serine instead of choline in their structure. Could you differentiate between lecithins and cephalins on the basis of the three tests to be performed in this experiment ... 

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