Aspartate chemical structure

It was snbseqnently discovered that the first enzyme in the pathway for isoleucine synthesis, which is threonine deaminase, was inhibited by isoleucine in an extract of E. coli. No other amino acid caused inhibition of the enzyme. Threonine deaminase is, in fact, the rate-limiting enzyme in the pathway for isoleucine synthesis, so that this was interpreted as a feedback control mechanism (Fignre 3.13(a)). Similarly it was shown that the hrst enzyme in the pathway for cytidine triphosphate synthesis, which is aspartate transcarbamoylase, was inhibited by cytidine triphosphate (Fignre 3.13(b)). Since the chemical structures of isoleucine and threonine, or cytidine triphosphate and aspartate, are completely different, the qnestion arose, how does isolencine or cytidine triphosphate inhibit its respective enzyme The answer was provided in 1963, by Monod, Changenx Jacob. 

Acamprosate (calcium acetylhomotaurine) has a chemical structure similar to homotaurine and GABA and appears to normalize N-methyl-D-aspartate (NMDA) receptor tone in the glutamate system. 

Fig. 1.1 Chemical structures of glutamate and aspartate and corresponding amines. Glutamine (a) glutamate (b) asparagine (c) aspartate (d) N-acetylaspartate (e) and N-acetylaspartyl-glutamate (f)...

Scheme 6 Chemical structure of poly(p-L-aspartate)s with various contents of para- (X) and meta-phenylazobenzyl (XI) units in the side chains.

Scheme 7 Chemical structure of copolypeptides containing p-phenylazoben-zyl-L-aspartate and n-octadecyl-L-aspar-tate residues (XII).155 56 ...

Substances related to MSG and purine 5 -ribonucleotides include peptides, amino acids (e.g. cysteine, homocysteine, cysteine S-sulfonic acid, aspartic acid, a-amino adipic acid, a-methyl glutamic acid, tricholomic acid, ibotenic acid), pyrrolidone carboxylic acid, 3-methyl thiopropyl amine, and others [2, 10], They are of less commercial interest than MSG, IMP, and GMP. Chemical structures of some of these substances are depicted in Fig. 3.53. Relative umami effects of some are shown in Tab. 3.49. Tricholomic acid and ibotenic acid have been found in the mushrooms Tricholoma muscarium and Amanita stroboliformis, respectively. 

Fig. 14 a, b Chemical structures of a poly (ethylene glycol)-Wock-poly(a, P-aspartate) (PEG- -PAsp) and polyethylene glycol)-Wock-poly(a, P-aspartamide) (PEG-b-PAspA), b poly (ethylene oxide)-Wocfc-polystyrene-protoporphyrin IX (PEO- -PS-PPIXZn) and crystal structure of horse radish peroxidase (HRP) the arrow marks the positioning of the cofactor... 

The incorporation experiments by Birch and co-workers (33,34), using [2- C]mevalonic acid, L-[l- 4C]alanine, and L-tryptophan, provided valuable information for the structural elucidation. Echinulin possesses two asymmetric centers, l-Alanine is obtained by acid hydrolysis, but another chiral center on the tryptophan moiety is easily racemized. Later, it was determined as the l form by microbioassay of the aspartic acid obtained by ozonolysis (35). Finally, the chemical structure 12 was confirmed by the stereoselective total synthesis of optically active echinulin by Kishi and co-workers (36) (Scheme 5). 

Fales and Pisano (1964) have discussed the gas chromatography of amines, alkaloids, and amino acids. Pollock and Kawauchi (1968) have resolved derivatives of serine, hydroxyproline, tyrosine, and cysteine, as well as racemic aspartic acid and tryptophan. VandenHeuvel and Horning (1964) have listed derivatives of steroids that can be separated. VandenHeuvel et al. (1960) first described the separation of bile acid methyl esters and Sjovall (1964) has extended the methods to bile acids. Gas liquid chromatography (GLC) is useful in the analysis of pesticides, herbicides, and pharmaceuticals (Burchfield and Storrs, 1962). Analysis of alkaloids, steroids, and mixtures of anesthetics and expired air are other examples of the application of this very useful technique. Beroza (1970) has discussed the use of gas chromatography for the determination of the chemical structure of organic compounds at the microgram level. 

Nicotine was isolated by Posselt and Reimann in 1828 [1], and subsequently the chemical structure was clarified [2-4]. As described later, the pyridine ring of nicotine is derived from nicotinic acid, which is biosynthesized from aspartic acid. Therefore, nicotine can also be described as an alkaloid derived from aspartic acid. On the other hand, the pyrroHdine ring is biosynthesized from ornithine.When DL-[5- C]-pyrroline-5-carboxyhc acid, a postulated biosynthetic precursor derived from ornithine, was incorporated into Nicotiana mstica, the incorporated rate (0.04%) was very low, and the 2 - and 5 -positions were equally labeled with (F ure). Consequently, it was estimated that the biosynthetic intermediate was not this compound but another symmetrical structure [5]. 

Figure 1 Chemical structures of comblike poly(y-alkyl-a,L-glutamate) (PyAG-n), poly(y8-alkyl-a,L-aspartate)s (PySAA-n), and poly(a-alkyl-/e,L-aspartate)s (PaAA-n) n indicates the number of carbons in the polymethylene side chain. The carbonyl position relative to the nitrogen atom is indicated by Greek letters.

FIGURE 15.3 Chemical structure of aspartic acid (2-(aininobutanedioic) acid) displaying the presence of one amine group and two carboxyl groups. 

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