Glutamic acid oxidase

A D-glutamic acid oxidase has been purified a himdredfold from Aaper-giUua ustus 103, 104). The enzyme deaminated n-glutamic acid and D-as-partic acid but had no activity with other DL-amino acids. The enzyme resembled that prepared from the octopus in its other properties 101). Thus, the optimum pH is 8 for both substrates and it appears, on the basis of inhibition and purification studies, that one enzyme is involved here as well. The enzyme is inhibited by 10 M concentration of KCN and p-chlo-romercuribenzoate but not by metal-binding agents. 

An estimation of the amount of amino acid production and the production methods are shown ia Table 11. About 340,000 t/yr of L-glutamic acid, principally as its monosodium salt, are manufactured ia the world, about 85% ia the Asian area. The demand for DL-methionine and L-lysiae as feed supplements varies considerably depending on such factors as the soybean harvest ia the United States and the anchovy catch ia Pern. Because of the actions of D-amiao acid oxidase and i.-amino acid transamiaase ia the animal body (156), the D-form of methionine is as equally nutritive as the L-form, so that DL-methionine which is iaexpensively produced by chemical synthesis is primarily used as a feed supplement. In the United States the methionine hydroxy analogue is partially used ia place of methionine. The consumption of L-lysiae has iacreased ia recent years. The world consumption tripled from 35,000 t ia 1982 to 100,000 t ia 1987 (214). Current world consumption of L-tryptophan and i.-threonine are several tens to hundreds of tons. The demand for L-phenylalanine as the raw material for the synthesis of aspartame has been increasing markedly. 

Choline-containing phospholipids have been determined in human serum using an IMER consisting of coimmobilized phospholipase D and choline oxidase [51]. Recently, immobilized glutamate oxidase was used to determine L-glutamic acid in culture media [52],... 

Glutamate dehydrogenase D-amino acid oxidase Standard solution D-alanine... 

Figure 8.6 The three dehydrogenase (oxidase) reactions in amino acid degradation. The enzymes are D-amino acid oxidase, glutamate dehydrogenase and proline oxidase (dehydrogenase). Biochemical details are given in Appendix 8.4.

CYTOCHROME P-450 REDUCTASE DIHYDROOROTATE OXIDASE FMN ADENYLYLTRANSFERASE GLUTAMATE SYNTHASE GLYCOLATE OXIDASE (S)-2-HYDROXY-ACID OXIDASE l-LACTATE DEHYDROGENASE (CYTOCHROME)... 

Many enzymatic assays have also been developed for the analysis of proteolytic products. Total amino acids in Cheddar cheese were determined by Puchades et al. (1990) using the L-amino acid oxidase enzyme. Glutamic acid has been quantified by flow injection analysis using glutamate dehydrogenase (Puchades et al., 1989) and using the Boehringer-Mannheim kit (McSweeney et al., 1993). 

Chen and Su [102] L-Glutamate L-Glutamic acid fermentation L-Glutamate oxidase/ onto a cellulose triacetate membrane Oxygen electrode ... 

N.F. Almeida and A.K. Mulchandani, A mediated amperometric enzyme electrode using tetrathiafulvalene and L-glutamate oxidase for the determination of L-glutamic acid, Anal. Chim. Acta, 282(2) (1993) 353-361. 

L-6-Hydroxynorleucine, a different key chiral intermediate used for synthesis of the vasopeptidase inhibitor Omapatrilat (Vanlev ), was prepared in 89% yield and > 99% optical purity by reductive amination of 2-keto-6-hydroxyhexanoic acid using glutamate dehydrogenase from beefliver (Hanson, 1999) (Figure 13.22). In an alternative process, racemic 6-hydroxynorleucine produced by hydrolysis of 5-(4-hydroxybutyl)hydantoin was treated with D-amino acid oxidase to prepare a mixture containing 2-keto-6-hydroxyhexanoic acid and L-6-hydroxynorleucine followed by the reductive amination procedure to convert the mixture entirely to L-6-hydroxynorleucine, with yields of 91-97% and optical purities of > 99%. 

A carboxylic side-chain of a glutamic acid (which is conserved in pyruvate decarboxylases, pyruvate oxidase and transketolase) forms a hydrogen bond to l N of ThDP, and thus keeps this nitrogen in the protonated form. The positive charge is delocalized to the 4 -NH2-group, making it possible for it to act as a proton donor [35,60]. 

Figure 2 Chemical conversion of 5-(4-hydroxybutyl)hydantoin (3) to racemic 6-hydroxynorleucine. Enzymatic conversion of racemic 6-hydroxynorleucine to L-6-hydroxy-norleucine (1) by D-amino acid oxidase and glutamate dehydrogenase.

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