Glutamic acid into optical isomers

Alanine, aspartic acid, glutamic acid, tyrosine, leucine, phenylalanine and also a-amino-n-caproic acid and a-aminobutyric acid have in this way been separated by Fischer into their optically active isomers. To these must be added ornithine which was synthesised by Sorensen in 1903, and separated into d- and 1-ornithine in 1905. 

The production of a-amino acids by chemical synthesis yields a mixture of DL forms. The D-fomi of glutamic acid has no flavor-enhancing properties and thus requires transformation into the optically active form insofar as monosodium glutamate is concerned. The three methods for separating the optical isomers are (1) preferential inoculation method ... 

Considering that sodium glutamate, like other amino acids, is contained in soy sauce, which is a traditional Japanese food, it is not surprising that Japan should have become interested very early in this type of fermentation. Firms like Ajinomoto and Kyowa Hakko dominate the world market for amino acids and particularly for glutamic acid and l-lysine. It is also through enzymes that the resolution of dl-methionine into its optical isomers is achieved since its laboratory synthesis yields the racemic form. 

Another major effect, found in PGA, is optical inversion of L-glutamate to D-glutamate residues. One implication of the radiation-induced optical inversion in proteins is that some modification of amino acids may pass undetected by the usual chemical analyses which do not distinguish between l- and D-isomers. Furthermore, introducing a D-amino acid residue into a protein could have a far-reaching effect on the secondary and tertiary structures, and this could have a more serious effect on the functional properties of the molecule than changes in the side chains. One biological property of PGA which is affected by irradiation in solution is its hydrolysis by proteolytic enzymes. The conformation of the polymer has a marked effect on its susceptibility to hydrolysis by certain enzymes 27), and we have... 

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