Mass spectra of some 5- and 6-substituted-2-pyridinecarboxylic acids. Nature of fragmentation step for loss of CO2

Moser, Russell J.; Brown, Ellis V.

doi:10.1002/oms.1210040156

Cited by 12 publications

(4 citation statements)

References 12 publications

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“…The electron impact (EI) mass spectrum is dominated by a fragment at m/z ϭ 113/115; loss of CO 2 from M ϩ ⅐ is characteristic for pyridine-2-carboxylic acids. The overall frag-mentation pattern closely resembles that reported for 6-chloropyridine-2-carboxylic acid (28).…”

Section: Resultssupporting

confidence: 79%

Distal Cleavage of 3-Chlorocatechol by an Extradiol Dioxygenase to 3-Chloro-2-Hydroxymuconic Semialdehyde

Riegert¹,

Heiss²,

Fischer

1998

J Bacteriol

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A 2,3-dihydroxybiphenyl 1,2-dioxygenase from the naphthalenesulfonate-degrading bacterium Sphingomonas sp. strain BN6 oxidized 3-chlorocatechol to a yellow product with a strongly pH-dependent absorption maximum at 378 nm. A titration curve suggested (de)protonation of an ionizable group with a pKaof 4.4. The product was isolated, purified, and converted, by treatment with diazomethane, to a dimethyl derivative and, by incubation with ammonium chloride, to a picolinic acid derivative. Mass spectra and 1H and 13C nuclear magnetic resonance (NMR) data for these two derivatives prove a 3-chloro-2-hydroxymuconic semialdehyde structure for the metabolite, resulting from distal (1,6) cleavage of 3-chlorocatechol. 3-Methylcatechol and 2,3-dihydroxybiphenyl are oxidized by this enzyme, in contrast, via proximal (2,3) cleavage.

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Section: Resultssupporting

confidence: 79%

Distal Cleavage of 3-Chlorocatechol by an Extradiol Dioxygenase to 3-Chloro-2-Hydroxymuconic Semialdehyde

Riegert¹,

Heiss²,

Fischer

1998

J Bacteriol

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“…The mass spectrum (Fig. 4B), which fully matched that of 5,6,7,8-tetrahydroquinoline, was dominated by a fragment at m/z ϭ 133, indicating loss of CO 2 from M ϩ , which is characteristic of pyridine-2-carboxylic acids (29,31). This indicates that the extradiol cleavage is proximal to the alicyclic ring, yielding 4-(2-oxocyclohexyl)-2-hydroxybuta-2,4-dienoic acid (Fig.…”

Section: Sequence Analysis Of Thnc and Other 12-dhndoxmentioning

confidence: 86%

Identification of an Extradiol Dioxygenase Involved in Tetralin Biodegradation: Gene Sequence Analysis and Purification and Characterization of the Gene Product

et al. 2000

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A genomic region involved in tetralin biodegradation was recently identified in Sphingomonas strain TFA. We have cloned and sequenced from this region a gene designated thnC, which codes for an extradiol dioxygenase required for tetralin utilization. Comparison to similar sequences allowed us to define a subfamily of 1,2-dihydroxynaphthalene extradiol dioxygenases, which comprises two clearly different groups, and to show that ThnC clusters within group 2 of this subfamily. 1,2-Dihydroxy-5,6,7,8-tetrahydronaphthalene was found to be the metabolite accumulated by a thnC insertion mutant. The ring cleavage product of this metabolite exhibited behavior typical of a hydroxymuconic semialdehyde toward pH-dependent changes and derivatization with ammonium to give a quinoline derivative. The gene product has been purified, and its biochemical properties have been studied. The enzyme is a decamer which requires Fe(II) for activity and shows high activity toward its substrate (V max , 40.5 U mg ؊1 ; K m , 18.6 M). The enzyme shows even higher activity with 1,2-dihydroxynaphthalene and also significant activity toward 1,2-dihydroxybiphenyl or methylated catechols. The broad substrate specificity of ThnC is consistent with that exhibited by other extradiol dioxygenases of the same group within the subfamily of 1,2-dihydroxynaphthalene dioxygenases.Tetralin (1,2,3,4-tetrahydronaphthalene) is an organic solvent widely used as a degreasing agent and solvent for fats, resins, and waxes; as a substitute for turpentine in paints, lacquers, and shoe polishes; and also in the petrochemical industry in connection with coal liquefaction (12). Tetralin is very toxic to bacteria because of its accumulation in the cell membranes, which leads to changes in structure and function (39,40), and also because of the formation of highly toxic hydroperoxides (11).Tetralin is a bicyclic molecule composed of an aromatic moiety and an alicyclic moiety sharing two carbon atoms. Just a few bacterial strains able to grow on tetralin as the only carbon and energy source have been reported (37), and very little is known about the utilization of this molecule by bacteria. Identification of accumulated intermediates during growth on tetralin suggests that some bacteria, such as Pseudomonas stutzeri AS39, initially hydroxylate and further oxidize the alicyclic ring (35), while others, such as Corynebacterium sp. strain C125, initially dioxygenate the aromatic ring, which is subsequently cleaved in the extradiol position (38). In spite of previous reports showing modification and utilization of tetralin (35,38,41,42), a complete biodegradation pathway has not yet been elucidated.Key enzymes in the pathways of aromatic compounds are the metal-dependent ring cleavage dioxygenases, which act on the corresponding catechol-type derivatives, cleaving them at the intradiol position (ortho cleavage) or the extradiol position (meta cleavage) (18). While intradiol dioxygenases typically depend on Fe(III), most extradiol dioxygenases depend on Fe(II), although one m...

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“…The mass spectra of picolinic acid and other pyridine carboxylic acids contain minor fragmentation peaks at m/e 55 and m/e 70 (13). These peaks were quite prominent in the spectra of both the zinc-binding ligand and a preparation of zinc-picolinic acid (Fig 5).…”

mentioning

confidence: 98%

Characterization and Quantitation of a Zinc-Binding Ligand in Human Milk

1980

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SummaryA low-molecular-weight zinc-binding ligand from human milk has been isolated and characterized. The ligand was isolated by chromatography on Dowex 50, Dowex 1, and Sephadex G-15 equilibrated with 0.153 mM Zn(N03)2. Mass spectroscopy, thinlayer chromatography, and infrared spectroscopy proved that the zinc-binding ligand isolated by this method from human milk is pyridine-2-carboxylic acid, commonly known as picolinic acid. The concentration of picolinic acid in human milk was 308 pM, the concentration in one brand of processed cow's milk was 20 pM, but picolinic acid was undetectable in a second brand of cow's milk and in four different infant formulas. Weanling rats fed supplemental picolinic acid absorbed significantly more dietary zinc and gained significantly more weight than rats fed an unsupplemented diet. The results suggest that the high bioavailability of zinc in human milk results from the presence of picolinic acid, a bidentate chelating ligand which facilitates zinc absorption from the intestine. SpeculationThe high bioavailability of zinc in human milk results from the presence of picolinic acid, a bidentate chelating ligand which facilitates zinc absorption from the intestine.Several clinical observations demonstrate that the bioavailability of zinc from human milk is much greater than that from cow's milk. In children affected with acrodermatitis enteropathica, an inherited disease that affects zinc metabolism (8), the symptoms characteristic of the disease do not generally appear until the child is weaned from the breast (1, 4, 5). Human milk has also been used successfully in the treatment of acrodermatitis enteropathica (15). Hambidge et al. (9) found that the plasma zinc concentration of breast-fed infants is not significantly different than that of healthy young adults. In contrast, the plasma zinc concentration of infants fed either zinc-supplemented formula or non-zinc-supplemented formula is significantly less than that of young adults. These observations suggest that human milk may contain a ligand or ligands which facilitate zinc absorption.To date, attempts to isolate zinc-binding ligands from biologic fluids have not been successful due to the fact that investigators have consistently used classical gel filtration chromatography. The problems encountered when attempting to detect and identify zinc-chelating ligands by the use of classical gel filtration have been discussed by Evans et al. (6). These authors have also described a technique, referred to as modified gel filtration chromatography, which can be used to reproducibly detect zinc-binding ligands in biologic fluids. This technique has now been adapted to isolate and quantitate a zinc-binding ligand in human milk. MATERIALS AND METHODS DETECTION OF ZINC-BINDING LIGANDSified gel filtration chromatography. A glass column 1.5 x 90 crr was packed with 44.4 g Sephadex G-15 (Pharmacia Fine Chemi. cals, Inc.) (18). The gel was equilibrated with 50 mM Tris acetate pH 7.4, that contained 0.1% NaN3 and 0.153 mM Zn(NO3)z. Thc buffer...

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Mass spectra of some 5- and 6-substituted-2-pyridinecarboxylic acids. Nature of fragmentation step for loss of CO2

Cited by 12 publications

References 12 publications

Distal Cleavage of 3-Chlorocatechol by an Extradiol Dioxygenase to 3-Chloro-2-Hydroxymuconic Semialdehyde

Distal Cleavage of 3-Chlorocatechol by an Extradiol Dioxygenase to 3-Chloro-2-Hydroxymuconic Semialdehyde

Identification of an Extradiol Dioxygenase Involved in Tetralin Biodegradation: Gene Sequence Analysis and Purification and Characterization of the Gene Product

Characterization and Quantitation of a Zinc-Binding Ligand in Human Milk

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