3-Hydroxyanthranilate

Figure 30-16. Formation of xanthurenate in vitamin Bg deficienqr. Conversion of the tryptophan metabolite 3-hydroxykynurenine to 3-hydroxyanthranilate is impaired (see Figure 30-15). A large portion is therefore converted to xanthurenate.

Muraki T, M Taki, Y Hasegawa, H Iwaki, PCK Lau (2003) Prokaryotic homologues of the eukaryotic 3-hydroxyanthranilate 3,4-dioxygenase and 2-amino-3-carboxymuconate-6-semialdehyde decarboxylase in the 2-nitrobenzoate degradation pathway of Pseudomonas fluorescens strain KU-7. Appl Environ Microbiol 69 1564-1572. 

Malherbe P, C Kohler, M Da Prada, G Lang, V Kiefer, R Schwarcz, H-W Lahm, AM Cesura (1994) Molecular cloning and functional expression of human 3-hydroxyanthranilic-acid dioxygenase. J Biol Chem 269 13792-13979. 

The analysis of amino acids involves chromatographic issues similar to those encountered in analysis of simple amines. Underivatized amino acids have, with a few exceptions, weak UV absorbance and a strong tendency to interact with stationary phases in undesirable ways. Underivatized amino acids are normally separated with ion exchange chromatography, then visualized post-column by reaction with ninhydrin, o-phthaladehyde (OPA), or other agents. Underivatized tryptophan and the metabolites kynurenine, 3-hydroxykynurenine, kynurenic acid, and 3-hydroxyanthranilic acid, were separated on a Partisphere 5-p ODS column with fluorescent detection.121... 

Reported redox potentials of laccases are lower than those of non-phenolic compounds, and therefore these enzymes cannot oxidize such substances [7]. However, it has been shown that in the presence of small molecules capable to act as electron transfer mediators, laccases are also able to oxidize non-phenolic structures [68, 69]. As part of their metabolism, WRF can produce several metabolites that play this role of laccase mediators. They include compounds such as /V-hvdi oxvacetan i I ide (NHA), /V-(4-cyanophenyl)acetohydroxamic acid (NCPA), 3-hydroxyanthranilate, syringaldehyde, 2,2 -azino-bis(3-ethylben-zothiazoline-6-sulfonic acid) (ABTS), 2,6-dimethoxyphenol (DMP), violuric acid, 1-hydroxybenzotriazole (HBT), 2,2,6,6-tetramethylpipperidin-iV-oxide radical and acetovanillone, and by expanding the range of compounds that can be oxidized, their presence enhances the degradation of pollutants [3]. 

The biosynthesis and metabolism of nicotinic acid in disease has received little attention metabolic studies deal mainly with normal animals and man (01, R5). After a tryptophan load dose, the main catabolites in the urine are nicotinuric acid, N1-methylnicotinamide, nicotinamide, quinolinic acid, kynurenine, 6-pyridone, anthranilic acid, and 3-hydroxyanthranilic acid. These excretory products were estimated... 

This iron-dependent enzyme [EC 1.13.11.6] catalyzes the reaction of 3-hydroxyanthranilate and dioxygen to yield... 

Alkaloids derived from nicotinic acid contain a pyridine nucleus. Nicotinic acid itself is synthesized from L-tryptophan via A-formylkynurenine, L-kynurenine, 3-hydroxykynurenine, 3-hydroxyanthranilic acid and quinolinic acid. 

Cleavage of 3-hydroxykynurenine by kynureninase (step g, Fig. 25-11) forms 3-hydroxyanthranilate, which is opened under the action of another dioxygenase (step h) with eventual degradation to acetyl-CoA, as indicated. In insects the reactive 3-hydroxyanthranilate is utilized in "tanning" reactions, e.g., coupling to tyrosine residues to toughen insect cuticles and walls of cocoons.214... 

Phenazines.—Results on the biosynthesis of microbial phenazines from shikimic acid (previously published in preliminary form cf. Vol. 5, p. 44 and Vol. 7, p. 27) are now available in full papers.53 Additional results are that 2,3-dihydro-3-hydroxyanthranilic acid (140) was not a precursor for iodinin (141), nor was... 

Figure 20.21 Catabolism of tryptophan by the serotonin and 3-hydroxyanthranilate pathways. B, B2, and B6 indicate the participation of coenzymes derived from the respective vitamins. Notice that tryptophan is glucogenic and ketogenic, because it produces alanine on the one hand, and acetoacetyl-CoA on the other.

In the catabolic pathway of tryptophan there are a number of reactions, starting with the oxidation product of 3-hydroxyanthranilate, that involve conjugated enamines, the... 

Kynureninase is involved in the oxidative metabolism of tryptophan. It catalyzes the conversion of L-kynurenine to anthranilic acid. The enzyme also converts L-3-hydroxykyneurenine to 3-hydroxyanthranilic acid. The latter compound has a high fluorescence, which is the basis for detection in this assay. 

Figure 9-53 Determination of lymphocyte kynureninase activity levels using HPLC. Enzyme activity is measured by quantification of formation of the product, 3-hydroxyanthranilic acid (3-HA A). (A) 3-HA A standard (12.0 nmol/L). (fl), Lymphocyte homogenate blank. (C) Lymphocyte 3-HAA production after 5 min of incubation in presence of 3-hydroxy-kynurenine. Peaks 1,3-HAA unmarked peaks are unidentified components. (From Ubbink et al., 1991.)...

Figure 8.4. Pathways of tryptophan metaholism. Tryptophan dioxygenase, EC 1.13.11.11 formylkynurenine formamidase, EC 3.5.1.9 kynurenine hydroxylase, EC 1.14.13.9 kynureninase, EC 3.7.1.3 3-hydroxyanthranilate oxidase, EC 1.10.3.5 picolinate carboxylase, EC 4.1.1.45 kynurenine oxoglutarate aminotransferase, EC 2.6.1.7 kynurenine glyoxylate aminotransferase, 2.6.1.63 tryptophan hydroxylase, EC 1.14.16.4 and 5-hydroxytryptophan decarboxylase, EC 4.1.1.26. Relative molecular masses (Mr) tryptophan, 204.2 serotonin, 176.2 kynurenine, 208.2 3-hydroxykynurenine, 223.2 kynurenic acid, 189.2 xanthurenic acid, 205.2 and quinolinic acid 167.1. CoA, coenzyme A.

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