Carboxylate moiety

Aspaityl proteinases are proteinases that utilize the terminal carboxyl moiety of the side chain of aspartic acid to effect peptide bond hydrolysis. 

Applications of peroxide formation are underrepresented in chiral synthetic chemistry, most likely owing to the limited stability of such intermediates. Lipoxygenases, as prototype biocatalysts for such reactions, display rather limited substrate specificity. However, interesting functionalizations at allylic positions of unsaturated fatty acids can be realized in high regio- and stereoselectivity, when the enzymatic oxidation is coupled to a chemical or enzymatic reduction process. While early work focused on derivatives of arachidonic acid chemical modifications to the carboxylate moiety are possible, provided that a sufficiently hydrophilic functionality remained. By means of this strategy, chiral diendiols are accessible after hydroperoxide reduction (Scheme 9.12) [103,104]. 

A substrate containing an amine carboxylate moiety is converted in an electrolyte solution in the presence of a strong acid to a cationic intermediate, an N-acyliminium cation, by electrooxidative reaction. This species is immediately reacted with an allylsilane [66, 67]. By nucleophilic reachon, C-C bond formahon is achieved. 

The above examples can be extended to the majority of older and newer active substances described in, e.g., The Pesticide Manual and to numerous relevant metabolites featuring hydroxyl or carboxyl moieties or even for conjugates however, there remain various active substances and metabolites that still require careful and extensive method development. 

Modified carboxylates, in which the carboxylate moiety forms part of a carboxymethoxy group, are also available. These are made by reaction of selected nonionic surfactants with chloroacetic acid. The result is a useful hybrid range, lacking the sensitivity of simple... 

Sulphosuccinates are of particular interest not only for their technical properties but also because structurally they combine the two hydrophile functions described earlier - the sulphonate and carboxylate moieties - in a single molecule (9.18). The sulphosuccinate diesters, however, are probably of greater commercial importance in textile processing than are the monoesters. The most important example is sodium dioctylsulphosuccinate (9.19), but the dinonyl, dimethylamyl and di-isobutyl analogues are also used commercially. As usual, a wide choice of hydrophobes is available and includes alcohols, lightly ethoxylated alcohols, alkanolamides and combinations of these. 

In a similar way, piperazinone derivatives can be prepared by either addition of the formed amine to a carboxylate moiety or by an intramolecular alkylation with a chloromethyl group present in the substrate [485]. 

Prados P, Fukushima T, Santa T et al (1997) 4-/V,/V-Dimethylam inosu 1 lbnyl-7 -N-(2-aminoethyl)amino-benzofurazan as a new precolumn fluorescence derivatization reagent for carboxylic acids (fatty acids and drugs containing a carboxyl moiety) in liquid chromatography. Anal Chim Acta 344 227-232... 

In this case, the principal resonance delocalization accompanying H-bond formation involves only the two alternative forms of the terminal carboxylate moiety,... 

At negative potentials in alkaline solutions, adsorbed NA retains K+ ions, as demonstrated by Auger spectroscopy, Figure 5-B. This retention of K+ ions is due to interaction of K+ with the pendant carboxylate moiety and greatly exceeds the amounts expected simply from diffuse double-layer interactions. Potential-dependence of K+ retention is essentially absent for compounds incapable of potential-dependent carboxylate pendancy (pyridine, picolinic acid, isonicotinic acid and 2,6-pyridine dicarboxylic acid). 

It is interesting to note that the C. maculatus compounds show an isoprene sub-unit which bears the unsaturation and the carboxylic moiety just like callosobruchusic acid 207. A propanoate (or methylmalonate) starter would formally complete the biogenesis of the structures. 

The haloalkane dehalogenase DhlA mechanism takes place in two consecutive Sn2 steps. In the first, the carboxylate moiety of the aspartate Aspl24, acting as a nucleophile on the carbon atom of DCE, displaces chloride anion which leads to formation of the enzyme-substrate intermediate (Equation 11.86). That intermediate is hydrolyzed by water in the subsequent step. The experimentally determined chlorine kinetic isotope effect for 1-chlorobutane, the slow substrate, is k(35Cl)/k(37Cl) = 1.0066 0.0004 and should correspond to the intrinsic isotope effect for the dehalogenation step. While the reported experimental value for DCE hydrolysis is smaller, it becomes practically the same when corrected for the intramolecular chlorine kinetic isotope effect (a consequence of the two identical chlorine labels in DCE). 

Hybrid triglycerides (RCOOCH2-CH(OCOR )-CH2OCOR"), i.e., containing zero, one, or two natural fatty acyl substituents, and three, two, or one active carboxylate moieties ... 

Hybrid pseudolipid analogues such as l,3-bis(acylamino)prop-2-yl esters (RCONHCH2-CH(OCOR )-CH2NHCOR), where R is a fatty acyl substituent and OCOR is the active carboxylate moiety. 

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