Ethanolamine carboxylates

We found a slight decrease of pH during reaction (0.1-0.2 pH units in the buffer zone of ethanolamine), which however translated as a decrease of about 20% of the concentration of OH ions. Above pH 10.5, the loss in OH ions reached about 40% of the initial concentration. This variation could be predicted by taking into account the need for replacement of the buffer ions at any time t 0 eletroneutrality implies that for every carboxylate liberated (i.e. every methoxylated galacturonate saponified), one molecule of ethanolamine is converted from the base form (EtNHj) to the salt form (EtNH, ). The concentration of the base and salt forms at... 

PGIP, purified fi om P.vulgaris hypocotyls [11], was immobilized to the sensor ch via amine coupling. A continuous flow of HBS buffer (5 pl/min) was mantained over the sensor surface. The carboxylated dextran matrix of the sensor surface was first activated by a 6-min injection of a mixture of N-hydroxy-succinimide and N-ethyl-N - (3-diethylaminopropyl) carbodiimide, followed by a 7-min injection of PGIP (lOng/pl in 10 mM acetate, pH 5.0). Hie immobilization procedure was con leted by a 7-min injection of 1 M ethanolamine hydrochloride to block the remaining ester groups. 

Figure 1.125 Carboxylate groups may be blocked with Tris or ethanolamine using a carbodiimide-mediated process.

Dissolve the macromolecule containing carboxylate groups to be blocked at a concentration of l-10mg/ml in 0.1 M MES, pH 4.7, containing 0.1 M Tris or ethanolamine. Other conditions may be used to perform this reaction. See Chapter 3, Section 1 for further details. 

A bacterial phosphatidylinositol specific phospholipase C (PI-PLC) had been available for many years before it was demonstrated to strip a number of membrane-bound proteins from eukaryotic cell surfaces [1], Such proteins are anchored by a PI moiety in which the 6 position of inositol is glycosidically linked to glucosamine, which in turn is bonded to a polymannan backbone (Fig. 3-10). The polysaccharide chain is joined to the carboxyl terminal of the anchored protein via amide linkage to ethanolamine phosphate. The presence of a free NH2 group in the glucosamine residue makes the structure labile to nitrous acid. Bacterial PI-PLC hydrolyzes the bond between DAG and phosphati-dylinositols, releasing the water-soluble protein polysac charide-inositol phosphate moiety. These proteins are tethered by glycosylphosphatidylinositol (GPI) anchors. 

Starting from ethanolamines 72, benzoxazepinones 73 [84—86], benzodiazepi-nones 74 [47, 86] and diazepanones 75 [47] have been produced depending on the starting carboxylic components. In the last case, classical Mitsunobu conditions gave unsatisfactory yields, and the conditions developed by Hanessian (SDI and NaH) were used instead. Using a-hydroxyacids 76, both benzoxazinones 69 [55] and benzoxazepinones 77 [55] have been accessed. The same compounds can also... 

By analogous fashion to imidazoline synthesis (Section 1.11.4.2.2), oxazolines have been introduced by modification of an acrylonitrile-containing polymer with ethanolamine (75JAP(K)75160392). In another modification (Scheme 99), chloromethylated polystyrene) (192) was treated with a Iithiated oxazoline (207) derived from reaction of 2-methyloxazo-Iine and butyllithium (78MI11106). The oxazoline groups were incorporated, in this study, as intermediates to carboxyl groups. 

Proteins with long C-terminal hydrophobic signal sequences may become attached to phosphatidylinositol-glycan anchors embedded in the plasma membrane (Fig. 8-13). An example is a human alkaline phosphatase in which the a carboxyl of the terminal aspartate residue forms an amide linkage with the ethanolamine part of the anchor. Attachment may occur by a direct attack of the -NH2 group of the ethanolanine on a peptide linkage in a transacylation reaction that releases a 29-residue peptide from the C terminus.118119 (See Chapter 29). 

In the synthesis of fatty acids the acetyl irnits are condensed and then are reduced to form straight hydrocarbon chains. In the oxo-acid chain elongation mechanism, the acetyl unit is introduced but is later decarboxylated. Tlius, the chain is increased in length by one carbon atom at a time. These two mechanisms account for a great deal of the biosynthesis by chain extension. However, there are other variations. For example, glycine (a carboxylated methylamine), under the influence of pyridoxal phosphate and with accompanying decarboxylation, condenses with succinyl-CoA (Eq. 14-32) to extend the carbon chain and at the same time to introduce an amino group. Likewise, serine (a carboxylated ethanolamine) condenses with... 

Methyl 3-ethoxycarbonylaminothiophene-2-carboxylates 211a derived from o-aminoesters 189 (Y = Me) and ethyl chloroformate were heated at 130-135°C with ethanolamine to give 3-(2-hydroxyethyl)thienopyrimidine-2)l//),4(3//)-diones 212 (89CPB1197, 89CPB2091). Several 3-[3-ethyl(4-substituted piperidine or piperazine)thienopyrimidine-2(l//),4-diones 214... 

The immobilization of anti-P-endorphin to the carboxymethylated dextran (which is on the surface of the resonant layer) was via NHS/EDC chemistry. Prior to antibody coupling, the carboxymethylated dextran was activated twice with 0.4 M EDC/0.1 M NHS for 10 min. Anti-P-endorphin was coupled twice to the dextran layer in 10 mM sodium acetate buffer, pH = 5.0, at 25 pg/ml to ensure maximum loading. After coupling, the free activated carboxyl group was blocked with 200 pi of 1 M ethanolamine for two minutes. Finally, the cuvette with immobilized anti-p-endorphin was washed twice with 20 mM HCl and twice with PBS/0.05% tween 20, to eliminate the non-covalently bound antibody. The binding of the peptides to the antibody was carried out in PBS, pH=7.4, at 25°C. After the baseline was established for 150 pi of PBS, 50 pi of 3 mg/ml (0.1 mg/ml/peptide) crude peptides in water was added to the cuvette and the binding was monitored. When equilibrium was achieved (approximately 10 min), the unbound peptides were flushed away. 

FIGURE 1 Detection of nearly 200 carboxyl-containing metabolites in urine by 2D 1H-15N HSQC NMR after tagging with 15N ethanolamine. Reproduced with permission from Ref. (21). 

The synthesis of glycosylphosphatidylinositol (GPI) anchors of proteins, including Thy-1 of neurons and lymphocytes, is primarily carried out within the lumen of the rough endoplasmic reticulum. The anchor consists of a phosphatidylinositol-glucosamine-mannosey-ethanolamine phosphate core that is linked to the a-carboxyl of the carboxyterminal amino acid of a protein (Figure 16-12). This addition takes place within minutes of... 

Scheme 13.26 gives the detail of the anchoring system to the protein. A phosphodiester bridge links the mannose to an ethanolamine molecule. The carboxylic end of the protein is attached to ethanolamine by an amide bond. 

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