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Ether phospholipids: phospholipids are known to have ether-linked "tails" instead of the usual ester linkage. [1] Ether on sn-1, ester on sn-2: "ether lipids" in the context of bacteria and eukaryotes refer to this class of lipids. Compared to the usual 1,2-diacyl-sn-glycerol (DAG), the sn-1 linkage is replaced with an ester bond. [1] [2] [3]
The long-chain bases, sometimes simply known as sphingoid bases, are the first non-transient products of de novo sphingolipid synthesis in both yeast and mammals. These compounds, specifically known as phytosphingosine and dihydrosphingosine (also known as sphinganine, [4] although this term is less common), are mainly C 18 compounds, with somewhat lower levels of C 20 bases. [5]
The first carbon of glycerol has a hydrocarbon chain attached via an ether, not ester, linkage. The linkages are more resistant to chemical attack than ester linkages are. The second (central) carbon atom has a fatty acid linked by an ester. The third carbon links to an ethanolamine or choline by means of a phosphate ester.
In sphingomyelin and glycolipids, the amino group of sphingosine is linked to FAs by an amide bond. In sphingomyelin the primary hydroxyl group of sphingosine is esterified to phosphoryl choline. Space-filling models of (a) sphingomyelin and (b) cholesterol. In glycolipids, the sugar component is attached to this group.
[4] [5] The amide group is called a peptide bond when it is part of the main chain of a protein, and an isopeptide bond when it occurs in a side chain, as in asparagine and glutamine. It can be viewed as a derivative of a carboxylic acid ( R−C(=O)−OH ) with the hydroxyl group ( −OH ) replaced by an amine group ( −NR′R″ ); or ...
Structurally, amino esters consist of three molecular components: a lipophilic part (ester); an intermediate aliphatic chain; a hydrophilic part (amine); The chemical linkage between the lipophilic part and the intermediate chain can be of the amide-type or the ester-type, and is the general basis for the current classification of local anesthetics.
Phosphatidylserine (PS) is the major acidic phospholipid class that accounts for 13–15% of the phospholipids in the human cerebral cortex. [7] In the plasma membrane, PS is localized exclusively in the cytoplasmic leaflet where it forms part of protein docking sites necessary for the activation of several key signaling pathways.
Therapeutic agents can be linked to dextran via an ester bond which can be hydrolyzed slowly by esterases to produce sustained, stable drug release. Drug-dextran complexes can also be formed by chemical linkage through an amide bond, which is hydrolyzed by amidase. Prodrugs coupled by amide bonds provide much slower drug release than by ester ...