Glutamate amino acids derived from

The importance of Heinrich Ritthausen s fundamental studies, 1862 to 1899, on analytical procedures for the determination of amino acids in proteins has been emphasized in the biographical sketches which have been presented by Osborne (210), Vickery (289), and Chibnall (47). It is of particular interest to note here the prediction made by Ritt-hausen about 1870 that the amino acid composition would prove to be the most adequate basis for the characterization of proteins. Ritthausen and Kreusler (230) were the first, in 1871, to determine amino acids derived from proteins, and some of the values which they found for aspartic and glutamic acids are given in Table III (cited by Chibnall, 47, and Vickery, 286). 

As early as 1905 Abderhalden (Al) isolated from the hydrolyzate of the nondiffusible fraction of human urine four amino acids, i.e., leucine, alanine, glycine, and glutamic acid, and detected two others phenylalanine and aspartic acid. Some amino acids derived from this fraction have been quantitatively determined by Albanese et al. (A3) who found in the amount of the nondiffusible fraction corresponding to one liter of urine as much as 32.8 mg tryptophan, 18.0 mg phenylalanine, 16.2 mg methionine, 15.2 mg cystine, 13.1 mg arginine, 6.7 mg histidine, and 3.9 mg tyrosine. 

Although the precision of analysis with our present technology is often 1 to 3 %, the quantitative release of many amino acids and amino acid derivatives from proteins is often difficult and lowers the overall precision. For example, if constant-boiling HCl (about 5.7 N) is used to hydrolyze a protein in vacuo at 110°C for 24 hr (these conditions are those most commonly used), the amounts of aspartic acid, asparagine, serine, threonine, glutamic acid, glutamine, valine, isoleucine, methionine, tyrosine, tryptophan, cysteine and cystine present in the... 

Glutamic Acid and Amino Acids Derived from It... 

GLUTAMIC ACID AND AMINO ACIDS DERIVED FROM IT... 

Drosophila DDC belongs to a family of pyridoxal-dependent decarboxylases that extends from prokaryotes to eukaryotic plants and animals. The members of this family show significant sequence similarity over much of their length, even though the individual proteins have quite different substrate specificities, including the amino acids tyrosine, tryptophan, phenylalanine, histidine, and glutamate, and the amino acid derivatives... 

Other components described in the literature which are able to enhance saltiness or umami taste are umami-tasting glutamate glycoconjugates (e.g. 18 or 19) [42], (S)-malic acid 1-0-D-glucopyranoside (morelid 20) [43], theogalline (21) [44], M-lactoyl ethanolamine (22) [45] and JV-gluconyl ethanolamines (23) [46], a-keto acids derived from amino acids (e.g. 24) [47] and some N-succinoyl derivatives of aspartic acid or glutamic acid (e.g. 25 and 26) [48]. 

FIGURE 22-15 Biosynthesis of six essential amino acids from oxalo-acetate and pyruvate in bacteria methionine, threonine, lysine, isoleucine, valine, and leucine. Here, and in other multistep pathways, the enzymes are listed in the key. Note that L,L-a,e-diaminopimelate, the product of step (HI), is symmetric. The carbons derived from pyruvate (and the amino group derived from glutamate) are not traced beyond this point, because subsequent reactions may place them at either end of the lysine molecule. 

In the fed state, when there is abundant protein and carbohydrate, dietary protein is hydrolyzed to amino acids. Those amino acids not required for protein synthesis are converted to 2-oxoacids by the aminotransferases. The 2-oxoacids are then converted into lipids and carbohydrate for storage. Glutamate dehydrogenase catalyzes the formation of ammonia from the excess amino groups derived from the amino acids this ammonia is excreted as urea. 

Poly(amino acid)s (PAAs) have also been used in drug delivery PEO-(l-aspartic acid) block copolymer nano-associates , formed by dialysis from a dimethyl acetamide solution against water, could be loaded with vasopressin. PLA-(L-lysine) block copolymer microcapsules loaded with fluorescently labelled (FITC) dextran showed release profiles dependent on amino acid content. In a nice study, poly(glutamate(OMe)-sarcosine) block copolymer particles were surface-grafted with poly(A-isopropyl acrylamide) (PNIPAAm) to produce a thermally responsive delivery system FITC-dextran release was faster below the lower critical solution temperature (LCST) than above it. PAAs are prepared by ring-opening polymerisation of A-carboxyanhydride amino acid derivatives, as shown in Scheme 1. 

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