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D T Gibson

Publications and source records attributed to D T Gibson.

At least 127 records · Page 7Linked to original sources
PubMed1974

Substrate specificity of the purified primary alcohol dehydrogenases from methanol-oxidizing bacteria.

Hyphomicrobium strain WC, Pseudomonas strain TP-1, and Pseudomonas strain W1 are capable of growth on methanol as the sole source of carbon and energy. Methanol-grown cells of each organism contain a primary alcohol dehydrogenase that has been purified to homogeneity. Each enzyme has a molecular weight of 120,000 and shows an in vitro requirement for phenazine methosulfate and ammonium ions for enzymatic activity. Normal aliphatic alcohols are oxidized rapidly by each enzyme. The presence of a methyl group on the carbon atom adjacent to the primary alcohol group lowers the enzymatic activity. This effect is reduced as the methyl substituent is moved further away from the hydroxyl group. The effect of other substituents on enzymatic activity is reported. Methanol, formaldehyde, and to a limited extent acetaldehyde are oxidized by the primary alcohol dehydrogenases. Higher aldehydes are not oxidized. A possible explanation for this specificity, with regard to aldehydes, is presented in terms of degree of hydration of the aldehyde.

Acetaldehyde↗
PubMed1974

Purification and propeties of (plus)-cis-naphthalene dihydrodiol dehydrogenase of Pseudomonas putida.

Cells of Pseudomonas putida, after growth with naphthalene as sole source of carbon and energy, contain an enzyme that oxidizes (+)-cis-1(r),2(s)-dihydroxy-1,2-dihydronaphthalene to 1,2-dihydroxynaphthalene. The purified enzyme has a molecular weight of 102,000 and apparently consists of four 25,500 molecular weight subunits. The enzyme is specific for nicotinamide adenine dinucleotide as an electron acceptor and also oxidizes several other cis-dihydrodiols. However, no enzymatic activity was observed with trans-1,2-dihydronaphthalene, or the K-region cis-dihydrodiols of carcinogenic polycyclic hydrocarbons.

Cell-Free System↗
PubMed1974

Bacterial metabolism of para- and meta-xylene: oxidation of a methyl substituent.

Pseudomonas Pxy was isolated on p-xylene as sole source of carbon and energy. Substrates that supported growth were toluene, p-methylbenzyl alcohol, p-tolualdehyde, p-toluic acid, and the analogous m-methyl derivatives, including m-xylene. Cell extracts prepared from Pseudomonas Pxy after growth with either p-xylene or m-xylene oxidized the p- and m-isomers of tolualdehyde as well as p-methylbenzyl alcohol. The same cell extracts also catalyzed a "meta" fission of both 3- and 4-methylcatechol. Treatment of Pseudomonas Pxy with N-methyl-N'-nitro-N-nitrosoguanidine led to the isolation of two mutant strains. Pseudomonas Pxy-40, when grown on succinate in the presence of p-xylene, accumulated p-toluic acid in the culture medium. Under the same conditions Pseudomonas Pxy-82 accumulated p-toluic acid and also 4-methylcatechol. When Pseudomonas Pxy-82 was grown on succinate in the presence of m-xylene, 3-methylcatechol and 3-methylsalicylic acid were excreted into the culture medium. A pathway is proposed for the initial reactions utilized by Pseudomonas Pxy to oxidize p- and m-xylene.

Alcohol Oxidoreductases↗
PubMed1974

Bacterial metabolism of para- and meta-xylene: oxidation of the aromatic ring.

Pseudomonas putida 39/D oxidized p-xylene to cis-3,6-dimethyl-3,5-cyclohexadiene-1,2-diol (cis-p-xylene dihydrodiol). The latter compound was isolated in crystalline form and its physical properties were determined. The cis configuration of the hydroxyl groups in the oxidation product was inferred from its ability to form an isopropylidene derivative with 2,2-dimethoxypropane. Acid treatment of cis-p-xylene dihydrodiol resulted in the formation of 2,5-dimethylphenol. A partially purified preparation of cis-toluene dihydrodiol dehydrogenase oxidized cis-p-xylene dihydrodiol to 1,2-dihydroxy-3,6-dimethylbenzene (3,6-dimethylpyrocatechol). P. putida 39/D oxidized m-xylene to a compound whose spectral and chromatographic characteristics were consistent with the structure 3,5-dimethyl-3,5-cyclohexadiene-1,2-diol. This product was very unstable, and all attempts to isolate it led to the formation of 2,4-dimethylphenol.

Anaerobiosis↗
PubMed1966

The metabolism of cresols by species of Pseudomonas.

1. A comparison of rates of oxidation of various compounds by whole cells indicated that protocatechuate was a reaction intermediate when a non-fluorescent species of Pseudomonas oxidized p-cresol. In contrast, a fluorescent Pseudomonas oxidized 3-methylcatechol and 4-methylcatechol when grown with p-cresol, but did not oxidize protocatechuate. 2. Heat-treated extracts of the fluorescent Pseudomonas oxidized catechol, 3-methylcatechol and 4-methylcatechol to ring-fission products, the spectroscopic properties of which were recorded. Rates of enzymic degradation of these products were also measured. 3. Acetic acid and formic acid were obtained by the action of a Sephadex-treated extract on 3-methylcatechol and 4-methylcatechol respectively. In each case 0.8mol. of the carboxylic acid was formed from 1.0mol. of substrate. 4. Dialysed extracts converted 3-methylcatechol into acetaldehyde and pyruvate, with 4-hydroxy-2-oxovalerate as a reaction intermediate. 4-Methylcatechol was converted first into 4-hydroxy-2-oxohexanoate and then into propionaldehyde and pyruvate. 5. The ring-fission product of catechol was formed from phenol by a fluorescent Pseudomonas, that of 3-methylcatechol was formed from o-cresol and m-cresol, and the ring-fission product of 4-methylcatechol was given from p-cresol. Propionate was readily oxidized by these cells after growth with p-cresol, but this compound was not attacked when phenol, o-cresol or m-cresol served as source of carbon. 6. Cell extracts appeared to attack only one enantiomer of synthetic 4-hydroxy-2-oxohexanoate.

Acetaldehyde↗
PubMed1965

The metabolism of beta-phenylpropionic acid by an Achromobacter.

1. When a species of Achromobacter grew with beta-phenylpropionate as carbon source, 2-hydroxy-beta-phenylpropionate and 2,3-dihydroxy-beta-phenylpropionate appeared in the growth medium. The concentrations of these compounds were maximal during exponential growth. 2. The cells contained an oxygenase that required Fe(2+) ions and cleaved the benzene nucleus between the adjacent carbon atoms that bear the side chain and one hydroxyl group of 2,3-dihydroxy-beta-phenylpropionate. 3. The ring-fission product, formed with the consumption of 1mol. of oxygen/mol. of substrate, was isolated and a chemical structure assigned. Sephadex-treated cell extracts converted 1mol. of this compound into 1mol. of 4-hydroxy-2-oxovalerate without oxygen consumption; succinic acid was also formed. 4. When Mn(2+) ions or Mg(2+) ions were added, dialysed extracts converted 4-hydroxy-2-oxovalerate into pyruvate and acetaldehyde, but the reaction did not proceed to completion.

Alcaligenes↗