Excitatory amino acids

Recent developments in the understanding of the molecular function of memory and other CNS-mediated processes have arisen from the multidisciplinary interplay of excitatory amino acid synthesis and medicinal chemistry, X-ray crystallographic structural protein analysis, molecular biology, pharmacology and physiology. This review seeks to place recent synthetic developments of EAA analogues in the wider pharmacological setting, illustrating the need for and importance of these compounds.     

Gas chromatography of amino acids.

This review summarizes all papers that have appeared on the gas chromatography of amino acids (including the iodoamino acids) and their enantiomers in the period 1956-mid-1974. It has been found that the methods used for analysis of amino acids can be divided into three classes: (1) degradative procedures and techniques for converting the amino acid into another chemical compound; (2) procedures based on esterification of the carboxyl group and derivatization of the a-amino and other reactive groups in at least two steps; and (3) procedures based on a simultaneous derivatization of the carboxyl and a-amino groups in one reaction medium. For the treatment of the amino acid or its alkyl ester, three approaches can be distinguished for the two latter cases, i.e., acylation, alkylation (including silylation) and condensation. Of the procedures used for the resolution of optical antipodes, two methods are discussed, namely analysis of diastereoisomers on optically inactive stationary phases and separation of enantiomers on optically active stationary phases.     

Production and utilization of amino acids.

The amino acid industry has been steadily expanding since monosodium glutamate was first marketed as a flavoring material in 1909. Its production has recently reached almost the 1 billion dollar level. Amino acids are produced by extraction from protein hydrolyzates, by fermentation with the aid of microorganisms, by enzymatic processes, and by chemical synthesis. To obtain natural L-amino acid, chemical synthesis generally requires two additional steps, i.e. optical resolution and racemization of the D isomer. The most important applications of amino acids include the fortification of plant food and feeds by supplementation of the deficient essential amino acid(s). Apart from their uses in the food industry, medical applications of amino acids (nutritional preparations and therapeutic agents) are becoming increasingly important.     

Silicon amino acids

The existence and gas phase stability of silicon analogues of three natural amino acids (i.e., silicon glycine, silicon alanine, and silicon valine) belonging to the novel class of compounds termed silicon amino acids (SiAA) are investigated theoretically on the basis of ab initio QCISD/aug‐cc‐pVTZ and MP2/aug‐cc‐pVTZ calculations. All molecules studied (in their gas phase canonical forms) are structurally comparable to their proteinogenic counterparts (i.e., glycine, l ‐alanine, and l ‐valine) and capable of forming several structural isomers as such. These higher energy isomers are characterized by small relative energies (not exceeding 4 kcal mol⁻¹). The simulated IR spectra of the Si‐Gly, Si‐Ala, and Si‐Val global minima are also presented and discussed.     

Empirical and ab initio calculations of thermochemical parameters of amino acids: IV. Non-Typical amino acids: Hydroxyamino acids, thioamino acids, and heterocyclic amino(imino) acids

Using a set of computational methods we calculated the basic thermochemical characteristics of the fifteen non-typical L-??-amino acids of hydroxyaminocarboxylic and thioaminomonocarboxylic series, and of some heterocyclic amino(imino)carboxylic acids.     

Quantitative gas-liquid chromatography of non-protein amino acids.

The quantitative gas--liquid chromatographic analysis of non-protein amino acids, in the presence of protein amino acids, is described. The amino acids were determined as their N-trifluoroacetyl n-butyl esters on an ethylene glycol adipate column. The relative molar responses of 38 amino acids are reported.     

Exotic amino acids. 4. Synthesis of methyl esters of some N-heteroamino-methylenemalonic acids

Isopropylidene N-hetarylaminomethylenemalonates, obtained from isopropylidene ethoxymethylenemalonate and 2-aminopyridine, 2-amino-5-methylpyridine, 2-aminopyrimidine, 7-amino-4-methylcoumarin, and 2-amino-3,5-diethoxycarbonyl-4-methylthiophene, undergo methanolysis at room temperature to give methyl esters of the corresponding N-hetarylaminomalonic acids. Isopropylidene N-hetarylaminomethylenenemalonate, containing a 2-aminothiazole group as a heterocyclic substituent, does not react under analogous conditions, but cyclizes upon heating at reflux to give 5-oxo-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid. 4-Oxo-9-R-4H-pyridino[1,2-a]pyrimidines are obtained upon the sublimation of isopropylidene N-pyridyl- and N-5-methylpyridylaminomethylenemalonates.Communication 3, see ref. [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 857–860, June, 2000.