Ester link

Although soaps have many physical properties in common with the broader class of surfactants, they also have several distinguishing factors. First, soaps are most often derived direcdy from natural sources of fats and oils (see Fats and fatty oils). Fats and oils are triglycerides, ie, molecules comprised of a glycerol backbone and three ester-linked fatty oils. Other synthetic surfactants may use fats and oils or petrochemicals as initial building blocks, but generally require additional chemical manipulations such as sulfonation, esterification, sulfation, and amidation. 

The ester link appears to enhance chain flexibility of an otherwise polymethylenic chain. At the same time it generally increases interchain attraction and in terms of the effects on melting points and rigidity the effects appear largely self-cancelling. 

If glycerol is reacted with phthalic anhydride three ester links can be made from each glycerol unit. Continued reaction will eventually cause the molecules to link up in a three-dimensional network in which, theoretically at least, the whole polymer mass becomes one giant molecule. 

In addition to one or more sugars, exopolysaccharides from prokaryotes commonly contain pyruvate ketals and various ester-linked organic substituents. These are only rarely found in eukaryotic exopolysaccharides. 

Acetate is the commonest ester-linked component of exopolysaccharides and does not contribute to their anionic nature. Less common ester-linked components, which may be found along with acetate in some exopolysaccharides, include ... 

The ending caine stems from cocaine, the first clinically employed local anaesthetic. Procaine and tetracaine are ester-linked substances, the others are amides. Amide bonded local anaesthetics usually contain two i s in their name, ester-bonded only one. In the structure drawings, the lipophilic portion of the molecule is depicted at the left, the amine at the right. The asterisk marks the chiral centre of the stereoisomeric drugs. Lipid solubility is given as the logarithm of the water octanol partition coefficient, log(P). 

Polyesters are defined as polymers containing at least one ester linking group per repeating unit. They can be obtained by a wide range of reactions, the most important being polyesterifications between dibasic acids and diols or their derivatives (Scheme 2.1). 

Nucleic acids are copolymers of four nucleotides joined by phosphate ester links. 

Piston F. Uauy C. Fu L. H. Langston J. Labavitch J. Dubcovsky J. (2010) Down-regulation of four putative arabinoxylan feruloyl transferase genes from family PF02458 reduces ester-linked ferulate content in rice cell walls / / Planta. N. 231. P. 677-691. 

A number of amide- and ester-linked fatty acids and (/ )-3-hydroxy acids are components of the lipid A part in the LPS from Gram-negative bacteria. The acids have been tabulatedand the chemistry of lipid A summarized. The most common acids in lipid A from Enterobacteriaceae are the saturated 12 0,14 0, and 16 0, and the (/ )-3-hydroxy-14 0, The last is linked to N-2 and 0-3 of the 2-amino-2-deoxy-D-glucopyranosyl residues, and the others are ester-linked to the hydroxy acid, as in the lipid A (44) of Salmonella minnesota. Other linear and branched fatty acids, unsaturated acids, S)-2- and (/ )-3-hydroxy acids, and 3-oxotetradecanoic acid are components of lipid A from certain different species. In the lipid A from Rhizobium trifolii, 2,7-dihydroxyoctanoic acid is linked as amide to a 2-amino-2-deoxy-D-gl ucopy ranosy 1 residue. ... 

In the peptidoglycan from some mycobacteria, the muramic acid is A -gly-colylated, not A-acetylated. As already mentioned, ester-linked lactic acid... 

These compounds constimte as much as 10% of the phospholipids of brain and muscle. StmcmraUy, the plasmalogens resemble phosphatidylethanolamine but possess an ether link on the sn- carbon instead of the ester link found in acylglycerols. Typically, the alkyl radical is an unsamrated alcohol (Figure 14-10). In some instances, choline, serine, or inositol may be sub-stimted for ethanolamine. 

The intracellular and plasma membranes have a complex structure. The main components of a membrane are lipids (or phospholipids) and different proteins. Lipids are fatlike substances representing the esters of one di- or trivalent alcohol and two aliphatic fatty acid molecules (with 14 to 24 carbon atoms). In phospholipids, phosphoric acid residues, -0-P0(0 )-O-, are located close to the ester links, -C0-0-. The lipid or phospholipid molecules have the form of a compact polar head (the ester and phosphate groups) and two parallel, long nonpolar tails (the hydrocarbon chains of the fatty acids). The polar head is hydrophihc and readily interacts with water the hydrocarbon tails to the... 

N. Ragendran, O. Matsuda. N. Imamura, and Y. Urushigawa, Variation in microbial biomass and community structure in sediments of eutrophic bays as determined by phospholipid ester-linked fatty acids, Appl. Environ. Microbiol. 58 562 (1992). 

B. H. Baird and D. C. White, Bioma.ss and eommunily strueture of the abyssal microbiota determined from the ester-linked phospholipids recovered from Venezuela Basin and Puerto Rico trench. sediment. Mar. Geol. 58 2 7 (1985). 

J. B. Guckert, M. A. Hood, and D. C. White, Phospholipid ester-linked fatty acid profile changes during nutrient deprivation of Vibrio cholerae increases in the irans/cis ratio and the proportions of cyclopropyl fatty acids, Appl. Environ. Microbiol. 52 794 (1986). 

In severe cases, paralysis may also affect the upper limbs. Recovery is usually slow and is not always complete. Tri-ort/20-cresyl phosphate (TOCP), an isomer found in tricresyl phosphate, was the first organophosphate ester linked to OPIDN, being responsible for an epidemic of paralysis in the southeastern United States that led to the name "ginger jake paralysis" (Smith 1930) (see Section 2.4). Current manufacturing processes for organophosphate ester hydraulic fluids are designed to minimize production of this isomer, although it is possible that fluids disposed of in the past may be contaminated. 

Figure 7 A novel, phosphate ester linking strategy [22] was used in the synthesis of phenyl phosphate-containing compound libraries, accomplished in 96-deepwell reaction blocks [23], Rigid, nonpeptide templates (A-group) and pY+3 substituents (B-group) satisfied the diversity sites of the molecules.

Metcalf CA III, Vu CB, Sundaramoorthi R, Jacobsen VA, Laborde EA, Green J, Green Y, Macek KJ, Merry TJ, Pradeepan SG, Uesugi M, Varkhedkar VM, Holt DA. Novel phosphate ester-linked resins the solid-phase generation of phenyl phosphate-containing compounds for SH2 inhibition. Tetrahedron Lett 1998 39 3435-3438. 

The affinity of the various stabilized dipeptidyl prodrugs to hPepTl in Caco-2 cells was also investigated [42, 43, 50]. In the case of the D-Glu-Ala ester-linked benzyl alcohols, an improved hPepTl affinity with increasing drug lipophilicity was observed [50], Furthermore, these model prodrugs are transported trans-epithelially across Caco-2 cells by virtue of a hPepTl-mediated process [50]. Preliminary hPepTl affinity studies made on Asp-Sar- and Glu-Sar-based (model)-... 

Different membrane lipids (ether linked in Archaea, phospho-ester linked in bacteria)... 

Enzyme-catalyzed transfer of KDO from CMP-KDO (127) into a lipid-A acceptor has been studied by Heath and coworkers,1 using a cell-free system from Escherichia coli O 111 J-5. LPS from the organism did not function as an acceptor, and only weak acceptor-activity was displayed147-148 by lipid A preparations obtained by mild, acid-catalyzed hydrolysis of LPS. Base-catalyzed, hydrolytic removal of the ester-linked, but not the amide-linked, fatty acid residues from lipid A resulted in an acceptor of maximal activity1 (see Scheme 38 compare Scheme 39). 

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