Amino-hydroxyanthranilate

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. 

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... 

In both syntheses the benzoxazole synthon 176 was prepared from methyl 5-hydroxyanthranilate (177), the amino group of which was trifluoroacetylated to give 178. Nitration of 178 gave the 6-nitro derivative 179 as the major product (in a 2 1 mixture with the 4-nitro compound) catalytic reduction to the 6-amino-5-hydroxy compound 180 was followed by refluxing with acetyl chloride in xylene to afford the benzoxazole 181, N-methylation of which yielded 176, the overall yield from 177 being 60% (94). 

Fig. 10. Structures of nonribosomally synthesized peptides of bacterial origin (1-6) and fungal origin (7-9). Me, N-methylated peptide boni Orn, ornithine 4-MHA, 4-methyl-3-hydroxyanthranilic acid Aad, aminoadipic acid Aeo, 2-amino-9,10-epoxy-8-oxodecanoic acid D-Hiv, D-hydroxyisovaleric acid Bmt, (4i )-4-[( )-2-butenyl]-4-methyl-L-threonine Abu, a-aminoisobutyric acid Sar, sarcosine. The boxes signify gene products for peptide synthetases composed of modules which activate and process the indicated amino acids...

In the same year paper chromatography was first attempted by Benassi (B4) for the simultaneous analysis of 8 tryptophan metabolites (kyn-urenine, 3-hydroxykynurenine, kynurenic acid, xanthurenic acid, anthra-nilic acid, 3-hydroxyanthranilic acid, 2-aminoacetophenone, and 2-amino-3-hydroxyacetophenone), separated by means of a mixtiue of methanol, n-butanol, benzene, and water and revealed through the fluorescence in ultraviolet light of 3655 A. Each compound elicits a different fluorescent color (cf. Table 1). 

A column of Amberlite IR-120, 0.9 X 28 cm, held constant at 37°C and formic acid-pyridine buffers are employed. With a buffer formic acid-pyridine 0.2 N, pH 2.50-2.60, kynurenic, xanthurenic, and o-amino-hippuric acids are eluted successively from the column. By increasing molarity and pH, respectively, to 0.3 N and 4.20 there emerge kynurenine, 3-hydroxyanthranilic acid, and 3-hydroxykynurenine, which are collected automatically in fractions of 2 ml. Figure 3 gives an example of chromatographic separation. 

Bladder and Kidney Cancer and Other Urological Diseases. The excretory pattern in cases of bladder tumor has been studied for many years in our laboratory (B5, B8) after Boyland and Williams (B18) had suspected that o-aminophenolic metabolites of tryptophan (i.e., 3-hydroxykynurenine, 3-hydroxyanthranilic acid, and 2-amino-3-hydroxy-acetophenone) might be endogenous agents of bladder cancer simi-... 

The relation of many of the simpler alkaloids to the aromatic amino acids is obvious. For example, germinating barley contains (241), besides tyrosine and tyramine, A -methyltyramine, JViV -dimethyltyramine (hordenine), and the trimethylammonium derivative (candicine). In this simple case the. AT-methylated derivatives are known to be derivable from isotopically labeled tyramine (538) and the methyl groups are known to arise from methionine by transmethylation (540, 586). Similarly AT-methyl derivatives of phenylethylamine, 3,4-dihydroxyphenylethylamine, and 3,4,5-trihy-droxyphenylethylamine are well known alkaloids (cf. review, 701). N-Methylated derivatives of tryptamine and hydroxytryptamine equally occur for example, eserine has an obvious relation to 5-hydroxy tryptamine. Methylated derivatives of metabolites of the aromatic amino acids also occur, for example, trigonelline (67), which is the betaine of nicotinic acid, and damascenine is probably similarly related to hydroxyanthranilic acid. 

Tryptophan is an essential amino acid involved in synthesis of several important compounds. Nicotinic acid (amide), a vitamin required in the synthesis of NAD+ and NADP+, can be synthesized from tryptophan (Figure 17-24). About 60 mg of tryptophan can give rise to 1 mg of nicotinamide. The synthesis begins with conversion of tryptophan to N-formylkynurenine by tryptophan pyrrolase, an inducible iron-porphyrin enzyme of liver. N-Formylkynurenine is converted to kynurenine by removal of formate, which enters the one-carbon pool. Kynurenine is hydroxylated to 3-hydroxykynurenine, which is converted to 3-hydroxyanthranilate, catalyzed by kynureninase, a pyridoxal phosphate-dependent enzyme. 3-Hydroxyanthranilate is then converted by a series of reactions to nicotinamide ribotide, the immedi-... 

Figure 2 NAD biosynthesis subsystem diagram. Major functional roles are shown by 4-6 letter abbreviations (explained in Table 1) over the colored background reflecting the key aspects or modules (pathways) that comprise NAD biosynthesis in various species. Catalyzed reactions are shown by solid straight arrows, and corresponding intermediate metabolites are shown as abbreviations within ovals Asp, L-aspartate lA, Iminoaspartate Qa, quinolinic acid Nm, nicotinamide Na, nicotinic acid NaMN, nicotinic acid mononucleotide NMN, nicotinamide mononucleotide RNm, N-ribosyInicotinamide NaAD, nicotinate adenine dinucleotide NAD, nicotinamide adenine dinucleotide NADP, NAD-phosphate Trp, tryptophan FKyn, N-formylkynurenine Kyn, kynurenine HKyn, 3-hydroxykynurenine HAnt, 3-hydroxyanthranilate and ACMS, a-amino-/3-carboxymuconic semialdehyde. Unspecified reactions (including spontaneous transformation and transport) are shown by dashed arrows.

Formation of Qa via aerobic degradation ofTrp (Kyn pathway) includes five enzymatic steps (1) oxidation of Trp to N-formyl kynurenine (FKyn) by Trp 2,3-dioxygenase (TRDOX), (2) deformylation of FKyn by kynurenine formamidase (KYNFA), (3) oxidation of Kyn to 3-hydroxykynurenine (HKyn) by kynurenine 3-monooxygenase (KYNOX), (4) conversion of HKyn into 3-hydroxyanthranilate (HAnt) by kynureninase (KYNSE), and (5) oxidation of HAnt by 3-hydroxyanthranilate 3,4-dioxygenase (HADOX) to a-amino-/3-carboxymuconic semialdehyde (ACMS) followed by its spontaneous cyclization to Qa (Scheme 2). This pathway and all respective... 

Im tierischen Organismus leiten sich die Pyridincarbonsauren von dem instabilen a-Amino-(3-carboxy-muconsauresemialdehyd (LXVIII) ab, der im Zuge des Tryptophanabbaues (218) fiber 3-Hydroxyanthranil-saure (LXVII) entsteht (s. Schema 12). 

The amino acid tryptophan is degraded by the higher plants to indolyl-3-acetic acid which is an important growth hormone for them, whereas bacteria usually degrade it to tryptamine, and mammals to 3-hydroxyanthranilic acid and thence to nicotinic acid which is an indispensable metabolite. 

Keller and coworkers succeeded in the preparation of several aromatic carboxylic acid-activating starter enzymes involved in the biosynthesis of actinomycin (4-methyl-3-hydroxyanthranilic acid) (105,113,114), triostin (qninoxaline-2-carboxylic acid) (105,115), and mikamycin (3-hydroxypicolinic acid) (105,116). More recently, related enzymes have been identified in the Actinomycetes that form the thiopeptides nosihep-tide and thiostreptone (117,118), and in the pristinamyctn biosynthetic system (de Crecy-Lagard V, personal communication). Whether direct acylation of the pantetheine-attached starter amino acid occurs, or an additional transferase frinction is required, has not been settled. 

Dehydroquinic acid, shikimic acid, and chorismic acid are carboxylated compounds containing a six-membered carbocyclic ring with one or two double bonds (Fig. 143). The secondary products derived from these substances either still contain the ring and the C -side chain of the acids (see the structure of the benzoic acid derivatives, of anthranilic and 3-hydroxyanthranilic esters, D 8, D 8.2, D 8.4 and D 8.4.1) or have additional rings (see the formulae of naphthoquinones and anthraquinones, D 8.1, of quinoline, acridine, and benzodiazepine alkaloids, D 8.3.2). The carbon skeletons may be substituted by isoprenoid side chains (see the structure of ubiquinones, D 8.3) and may carry different functional groups, e.g., hydroxy, carboxy, methoxy, and amino groups. 

The secondary products derived from anthranilic acid (o-amino benzoic acid) may carry additional substituents at the aromatic ring, e.g., hydroxy groups (see formula for hydroxyanthranilic acid) or at the carboxyl and the amino group. The latter substituents may form additional rings. 

Hydroxyanthranilic acid (2-amino-3-hydroxybenzoic acid) may be substituted at the functional groups, e.g., by methylation or by substituents forming additional rings. 

Degradation of L-tryptophan in most organisms proceeds via L-kynurenine, 3-hydroxy-L-kynurenine, 3-hydroxyanthranilic acid and quinolinic acid to acetyl Co A and CO2 (Fig. 244). Anthranilic acid formed as an intermediate may be recycled to L-tryptophan (see above). The ring of 3-hydroxyanthranilic acid is cleaved by a dioxygenase (C 2.5). The x-amino-/3-carboxymuconic acid-e-semialdehyde formed either undergoes a cis trans isomerization of the Zl -double bond and cyclization to quinolinic acid, a compound synthesized in microorganisms and plants from aspartic acid and D-glyceraldehyde-3-phosphate (D 16.2). On the other hand o -amino-/3-carboxymuconic acid-e-aldehyde may be de-carboxylated and is then the immediate precursor of NH3, acetic acid and COg. 

Picolinic Carboxylase. An enzyme in liver decarboxylates the original carboxyl group of 3-hydroxyanthranilic acid from the oxidation product. The product of the decarboxylation is picolinic acid. Picolinic carboxylase has no known cofactors. The mechanism of its action is thought to involve a temporary loss of the double bond during decarboxylation. This permits rotation of the amino group into a position favoring condensation to form the pyridine ring (XII). 

A number of experiments have been carried out with to establish that the amino nitrogen of 3-hydroxyanthranilic acid is the precursor of the pyridine ring nitrogen. In one of these experiments a mutant strain of Neurospora utilizing 3-hydroxyanthranilic acid for growth... 

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