Aspartic acid oxidase

Aspartic acid oxidase (rabbit kidney) N-methyl-L-amino acid + L-amino acid + H CHO... 

The enzyme systems to be considered here are those which are relatively specific for a single amino acid and which yield ammonia as a result of the primary oxidation. Only three systems have been investigated sufficiently to warrant inclusion at this time glutamic acid dehydrogenase, glycine oxidase, and D-aspartic acid oxidase. 

D-Aspariic Acid Oxidase. Still et al. reported that rabbit kidney and liver contain a soluble enzyme which catalyzes the aerobic oxidation of D-aspartate to oxalacetate plus NH3 with the formation of hydrogen peroxide. In a later study by Still and Sperling the D-aspartic acid oxidase was resolved and reactivated by the addition of FAD. The purified enzyme showed about one-sixth the activity with D-glutamate this, according to these workers, is best explained by the presence of a D-glu-tamic acid oxidase. The activity of n-aspartic acid oxidase is higher than that of D-amino acid oxidase in rabbit kidney and liver, and they are of the same order of activity in pig kidney. In contrast to pig kidney o-amino acid oxidase, which is inhibited by benzoic acid, the D-aspartic acid oxidase was unaffected. 

The D-aspartic acid oxidase of Still and co-workers is found in rabbit kidney as well as liver and is a soluble enzyme which can be obtained in high concentration in the supernatant fluid of the homogenates. Although no soluble coenzyme requirement has been found for the oxidase, it forms H2O2, which suggests that it is a firmly bound flavoprotein. 

ACYL-CoA DEHYDROGENASES ADENYLYLSULEATE REDUCTASE ALCOHOL OXIDASE AMINE OXIDASES d-AMINO acid DEHYDROGENASE l-AMINO acid DEHYDROGENASE d-AMINO ACID OXIDASE l-AMINO ACID OXIDASE d-ASPARTATE OXIDASE BENZOATE 1,2-DIOXYGENASE... 

Wake, K., Yamazaki, H., Hanzawa, S., Konno, R., Sakio, H., Niwa, A., Hori, Y. Exaggerated responses to chronic nociceptive stimuli and enhancement of N-methyl-D-aspartate receptor-mediated synaptic transmission in mutant mice lacking D-amino-acid oxidase, Neurosci. Lett. 2001, 297, 25-28. 

Thiosulfate cyanide sulfurtransferase symmetry in 78 TTiiouridine 234 Three-dimensional structures of aconitase 689 adenylate kinase 655 aldehyde oxido-reductase 891 D-amino acid oxidase 791 a-amylase, pancreatic 607 aspartate aminotransferase 57,135 catalytic intermediates 752 aspartate carbamyltransferase 348 aspartate chemoreceptor 562 bacteriophage P22 66 cadherin 408 calmodulin 317 carbonic acid anhydrase I 679 carboxypeptidase A 64 catalase 853 cholera toxin 333, 546 chymotrypsin 611 citrate synthase 702, 703 cutinase 134 cyclosporin 488 cytochrome c 847 cytochrome c peroxidase 849 dihydrofolate reductase 807 DNA 214, 223,228,229, 241 DNA complex... 

List of Abbreviations CD/MRV, Common Disease/Multiple Rare Variants DAAO, D-amino acid oxidase DAOA, D-aminoacid oxidase activator EST, expression sequence tag GEO, Gene Expression Omnibus MAF, minor allele frequency NIMH, National Institute of Mental Health NMDA, N-methyl D-aspartate RT-PCR, reverse transcription-PCR... 

Such interference falls into two classes competitive substrates and substances that either aaivate or inhibit the enzyme. With some enzymes, such as urease, the only substrate that reacts at reasonable rate is urease hence, the urease-coated electrode is specific for use (59, 165). Likewise, uricase acts almost specifically on uric acid (167), and aspartase on aspartic acid (8, 168). Others, such as penicillinase and amino oxidase, are less specific (63,169,170). Alcohol oxidase responds to methanol, ethanol, and allyl alcohol (171, 172). Hence, in using electrodes of these enzymes, the analyte must be separated if two or more are present (172). Assaying L-amino acids by using either the decarboxylative or the deaminating enzymes, each of which acts specifically on a different amino... 

A combination of D-amino acid oxidase and L-amino transferase is an example of a deracemization by stereoinversion. The product is an L-amino acid. The reaction catalyzed by amino transferase has an equilibrium constant close to unity, a very unpractical situation leading to uncomplete transformation and to the production of almost inseparable mixtures of amino acids (at least two, the amino acid product and the amino add used as an amino donor). For preparative purposes it is therefore mandatory to shift the equihbrium to the product side. A recent example of a deracemization procedure based on this coupled enzymatic system is the preparation of L-2-naphthyl-alanine 6 as illustrated in Scheme 13.9 [28]. The reaction occurs in one pot with initial oxidation of the D-amino acid catalyzed by D-amino acid oxidase from Rhodotonda gracilis. The hydrogen peroxide that is formed in stoichiometric amounts is decomposed by catalase. The a-keto add is the substrate for L-aspartate amino transferase (L-Asp amino transferase), which is able to use L-cysteine sulfinic acid 7 as an amino donor. 

The flavin co-factor is reduced with concomitant oxidation of the amino acid into the corresponding imino acid, which spontaneously hydrolyzes to the a-keto acid and ammonia the flavin co-factor is then reoxidized by molecular oxygen with the production of hydrogen peroxide. Both D- and L-amino acid oxidases deaminate a variety of amino acids, particularly those having a hydrophobic side chain, but are practically inactive on acidic amino acids (which are deaminated by specific glutamate and aspartate oxidases) and are strictly stereospecific. 

D-Aspartate oxidase L-Amino-acid oxidase D-Amino-acid oxidase Amine oxidase (flavin-containing) Amine oxidase (copper-containing) D-Glutamate oxidase Ethanolamine oxidase Putrescine oxidase L-Glutamate oxidase L-Lysine oxidase... 

Like laccase and ceruloplasmin, ascorbate oxidase is an acidic protein, with aspartic acid and glutamic acid in excess over histidine, lysine, and arginine. For the amino acid composition see the detailed data in References 3 and 18. Unlike laccase, ascorbate oxidase has a relatively low carbohydrate content, 2.4% vs. approximately 45% (29). 

Another example of a coupled enzyme reaction demonstrates the versatility of the transaminase system in biocatalysis. Using a racemic d,L-amino acid mixture as the starting material, the enzyme D-amino acid oxidase from Trigonopsis mriabilis will convert the D-amino acid in the mixture selectively into the corresponding 2-keto acid. The L-amino acid of the d,l- pair is neither a substrate nor an inhibitor of d-amino acid oxidase. If a transaminase is present in the same reaction mixture, the 2-keto acid can be transaminated in the presence of L-aspartate to the corresponding L-amino acid. The entire reaction can be driven to completion as described previously by decarboxylation of the oxaloacetate. Thus, in a single pot, racemic d,l-amino acids can be convened directly into optically active L-amino acids (Fig. 12.7-11). 

Among the enzymes catalyzing oxidations of carbon nitrogen bonds, the amino acid oxidases (AAO, E.C. 1.4.3.x) are the most interesting for synthetic applications. Compared to some specific amino acid oxidases such as aspartate oxidase or glutamate oxidase, the two d- and L-amino acid oxidases (E.C. 1.4.3.2 for l-AAO and E.C. 1.4.3.3 for d-AAO) are advantageous on account of their broad substrate... 

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