Amino acids names

The Common a-Amino Acids (names and abbreviations below structures)... 

Enantiomerically pure 4,5,6-trihydroxy-norleucins (for instance 325) were obtained (197) from the hex-2-enono-1,4-lactone-2-mesylates (such as 152). These butenolides were stereoselectively hydrogenated to afford, upon treatment with sodium azide, the C-2-inverted derivatives, such as 324. Reduction of the azide function and hydrolysis of the acetal group gave the amino acids (namely 325), which were converted into lactones in acid media. 

In the previous section, we have examined peptides composed of nonpro-teinogenic amino acids, namely artificial, D-, f3-, and y-amino acids. In this section, we move even further afield from natural peptides. Given inconsistent usage in the literature, we begin by specifying the definitions used here [7][11][139][181][182][184-188][229]. 

In addition to esters of a-amino acids, Table 8.9 also lists four prodrugs of metronidazole where the pro-moieties are longer-chain amino acids, namely... 

Racemic -amino acids, namely 3,3-ethano- -alanine (193 a) and its spiro-cyclopropanated analog 193b, have been prepared by simple one-step hydrogenolytic reduction and deprotection of the primary Michael adducts 94 b and 94 d (Scheme 57) [9,21b]. As methyl esters cannot be deprotected under these conditions, only reductive dechlorination and debenzylation was observed for compounds 91t,u (Scheme 57) [7k]. This looks promising for the construction of... 

Throughout this section, amino acid names without a configurational designation are to be understood as referring to the l-isomer. 

Because of their unique biological functions, a significant and growing part of new drug discovery and development is focused on this class of biomolecules. Their biological functions are determined by the exact arrangement, or sequence of different amino acids in their makeup. There are 20 naturally occurring amino acids, 8 of which are essential amino acids, namely, l-isoleucine, L-leucine, L-lysine, L-methionine, L-phenylalanine, L-valine, l-threonine, and L-tryptophan. 

In 1976, Achiwa 40) synthesized the first functionalized chiral hiphosphanes starting with an optically active amino acid, namely 4-hydroxy-(S)-proline (12). 

Each amino acid name has an associated three-letter abbreviation and a one-letter symbol (Figure 1.7). The one-letter codes are determined by the following rules ... 

Amino acids named according to side chain... 

The same amino acid, named as 5-oxoproline, is an intermediate in the y-glutamyl cycle. The name pyro-glutamate suggests formation involving dehydration via heat (fire) from glutamate. 

Microdialysis experiments show that BEO (0.5 ml/kg) did not affect basal amino acid levels, whereas it significandy reduced the efflux of excitatory amino acid, namely aspartate and glutamate, in the frontoparietal cortex typically observed following MCAo (Fig. 2). Extracellular levels of glycine, GABA,... 

The specificities are determined by the side chains of the amino acids on either side of the peptide bond that is hydrolyzed in the polypeptide chain. For the endopeptidases, it is the side chain of the amino acid contributing the carbonyl group of the peptide bond that determines whether the substrate will bind. Thus, chymotrypsin hydrolyzes peptide bonds where the carbonyl group is from one of the aromatic amino acids, namely, phenylalanine, tyrosine, or tryptophan. The specificities are listed in Table 15.3. 

The mode of biosynthesis of none of these alkaloids is known but, in the case of the iboga group, some guesses have been made (39, 63, 64), all of which start from the amino acids, tryptophan and dihydroxy-phenylalanine, and involve a fission of the latter s aromatic ring. A more sophisticated approach (65), starting from precursors of the aromatic amino acids, namely shikimic and prephenic acids, is apparently not in agreement with recent work on other indole alkaloids (66). The genesis of most indole alkaloids appears to stem from tryptophan and three... 

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