Dicarboxylic amino acids

SLC1A1) Kidney epithelium Resorption of dicarboxylic amino acids... 

The relationship of the dicarboxylic amino acids, aspartic and glutamic acids to this process has also been studied (106). This investigation has been facilitated by a quantitative method for the codetermination (23) of the dehydrogenation indicator, resazurin, and its reduction product, resorufin. The wood destroying molds used were Trameles cinnabarina and Lentinus lepideus. 

NMDA receptor agonists are typically short-chain dicarboxylic amino acids such as glutamate, aspartate and NMDA. Acting at a site on the NR2 subunit, glutamate is the most potent endogenous agonist in the... 

In the course of studies on aminoaciduria in Fanconi s syndrome, Dent (Dl) isolated from the urine of the subject investigated a simple peptide identified as serylglycylglycine. Carsten (Cl) found in normal urine several peptides containing in every case one of the dicarboxylic amino acids. He discovered also two tetrapeptides, one of them consisting of equimolar amounts of aspartic acid and glycine, and the second composed of glycine, alanine, and glutamic acid in the ratio 2 1 1. The first of these tetrapeptides was also found in the urine of a patient with rheumatoid arthritis. 

Activated esters (see Section 2.9) with 1-hydroxybenzotriazole as a catalyst are employed — pentafluorophenyl or 4-oxo-3,4-dihydrobenzotriazin-3-yl esters in particular for continuous-flow systems and special cases such as dicarboxylic amino acids. Other activated esters are not reactive enough. An alternative is preparation of benzotriazolyl esters using a carbodiimide followed by addition of the solution to the peptide-resin. 

Ninhydrin (triketohydrindene hydrate) reacts with an amino acid when heated under acidic conditions (pH 3-4) to produce ammonia, carbon dioxide and a blue-purple complex. This reaction forms the basis of many widely used methods (Figure 10.11). One mole of carbon dioxide is liberated from each mole of amino acid, exceptions being the dicarboxylic amino acids, which produce two moles of carbon dioxide, and the a-imino acids, proline and hydroxyproline, which do not produce carbon dioxide. Although this formed the basis of a gasometric technique, colorimetric methods are now the most common. 

ASP is caused by eating shellfish contaminated with one or more of three domoic acid derivatives, which are excitatory neurotoxic amino acids (Baden and Trainer, 1993). Domoic acid is produced by the diatom Nitzchia pungens and accumulates in mussels, specifically Mytilus edulis (Baden and Trainer, 1993). Domoic acid is similar in structure to the excitatory dicarboxylic amino acid, kainic acid, and has an antagonistic effect at the glutamate receptor. Both... 

Alternatively, oxazolones have been used as reagents to activate and to couple N-protected dicarboxylic amino acids wherein the carboxylate moiety acts as the nucleophile. For example, 2,4-dimethyl-5(4//)-oxazolone 255 reacts with N-benzyloxycarbonyl-L-aspartic acid to give a mixture of the anhydrides 256 and 257. Subsequent reaction of 256 and 257 with phenylalanine methyl ester hydrochloride and A-methylmorpholine produces a mixture of the a-isomer 258 and p-isomer 259 of Al-benzyloxycarbonyl-aspartylphenylalanine methyl ester (Scheme 7.83). °... 

Mainly two types of building blocks containing vicinal lipid chains have been developed these are based on diesters (10 and 11) or di-./V-(alkyl)amides (12) of the dicarboxylic amino acids, IV-dialkylamides of dicarboxylic acids (13 and 14), as well as on diesters of glycerol and related derivatives (15-21) (Scheme 14). 

Lipophilic Building Blocks Based on Dicarboxylic Amino Acid Esters and... 

In addition to these major processes, many other chemical events also occur. Mitochondria concentrate Ca2+ ions and control the entrance and exit of Na+, K+, dicarboxylates, amino acids, ADP, P and ATP, and many other substances.16 Thus, they exert regulatory functions both on catabolic and biosynthetic sequences. The glycine decarboxylase system (Fig. 15-20) is found in the mitochondrial matrix and is especially active in plant mitochondria (Fig. 23-37). Several cytochrome P450-dependent hydroxylation reactions, important to the biosynthesis and catabolism of steroid hormones and... 

From kinetic (57) and chemical modification (58) studies, Hurst et al. concluded that the catalytic residues in a cellulase from Aspergillus niger are a carboxylate anion (pKa 4.0-4.5) and a protonated carboxyl group (pKa 5.0-5.5) with tryptophan and dicarboxylic amino acid residues involved in substrate binding. 

A direct K+ requirement for translocation has, however, been reported for glutamic acid transport in brain (Kanner and Schuldiner, 1987 Carlson et al., 1989). The dicarboxylic amino acids appear to be transported largely by specific transporters which do not participate in neutral amino acid transport. Recent studies, both in reconstituted systems and the expression of the cloned transporter, have confirmed the K+ requirement (see below). 

The fractional equilibrium concentration of glutamic acid ( pKal = 2.2, pKa2 = 4.3, and pKa3 = 9.4) or any other dicarboxylic amino acid is similar to Figure 2.14. 

The transporters have overlapping specificities. Thus, there is one transporter (called system L) for leucine and neutral amino acids with branched or aromatic side chains, another for basic amino acids (the Ly system), and a low-activity carrier (the dicarboxylate system) for dicarboxylic amino acids. 

In earlier work in this field, an excess of either basic or dicarboxylic amino acids in the reactants was thought to be essential for obtaining thermal polymers of reasonable molecular weight in substantial yield. Recently, however, three independent reports have appeared on the preparation of a third general type of proteinoid, termed neutral proteinoid. By using reactants that contained excess neutral amino... 

Cannan, R. R. The Estimation of the Dicarboxylic Amino Acids in Protein... 

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