Naphthalene dioxygenase, a key enzyme in the dihydroxylation of naphthalene, is encoded by the pl... more Naphthalene dioxygenase, a key enzyme in the dihydroxylation of naphthalene, is encoded by the plasmid pN3, responsible for naphthalene metabolism in Pseudomonas fluorescens N3. The naphthalene dioxygenase, including all the sequences for its expression and the regulatory region, has been localized on the 4.3-kb HindIII-ClaI fragment and on the 3.5-kb HindIII fragment of the plasmid pN3, by Southern analysis using as probes nahA and nahR genes, the homologous genes of the plasmid NAH7 from Pseudomonas putida G7. We cloned in Escherichia coli JM109 the dioxygenase gene and its regulatory region and developed an efficient bacterial system inducible by salicylic acid, able to produce dihydrodiols. E. coli containing recombinant plasmids carrying the dioxygenase gene were analysed for their potential as a biocatalytic tool to produce dihydrodiols from different naphthalenes with the substituent on the aromatic ring at the alpha or beta position. The dihydrodiols, identified by HPLC (hig...
... Silvana Bernasconi a , Fulvia Orsini a , Guido Sello Corresponding Author Contact Information... more ... Silvana Bernasconi a , Fulvia Orsini a , Guido Sello Corresponding Author Contact Information , E-mail The Corresponding Author , a , Andrea Colmegna b , Enrica Galli b and Giuseppina ... 4. F. Beltrametti, AM Marconi, G. Bestetti, C. Colombo, E. Galli, M. Ruzzi and E. Zennaro. ...
... 2, pp. 105 to 118, 1989 0898-5529]89 $3.00+.00 Printed in Great Britain Pergamon Press plc Re... more ... 2, pp. 105 to 118, 1989 0898-5529]89 $3.00+.00 Printed in Great Britain Pergamon Press plc Residual Charges On Atoms In Organic Structures: Molecules Containing Charged and Backdonating Atoms Luca Baumer, Giordano Sala and Guido Sello* Dipartimento di Chimica ...
... All rights reserved PH: S00404020(96)005583 00404020 96 15.00 + 0.00 Reactivity of Glucosyl R... more ... All rights reserved PH: S00404020(96)005583 00404020 96 15.00 + 0.00 Reactivity of Glucosyl Radical in the Presence of Phenols Angelo Alberti, +a Maria A. Delta Bona, a Dante Macciantelli,a Francesca Pelizzoni,b Guido Sello,b ... Larkin, JP; Norman, ROCJ Chem. Soc. ...
The use of two oxidoreductases (an aldoketo reductase from Escherichia coli JM109 and an alcohol ... more The use of two oxidoreductases (an aldoketo reductase from Escherichia coli JM109 and an alcohol dehydrogenase from Lactobacillus brevis) has demonstrated that it is possible to prepare enatiomerically pure diols in a one-pot operation. The reactions were applied to the synthesis of (1R)-1-[3-(hydroxymethyl)phenyl]ethanol and (1S)-1-phenylethane-1,2-diol, using a two-step procedure. The yield is nearly quantitative and the enantiomeric purity is greater
... Alkylation of Chiral Phosphonoglycine Equivalents: Asymmetric Synthesis of Diethyl AminocxAlk... more ... Alkylation of Chiral Phosphonoglycine Equivalents: Asymmetric Synthesis of Diethyl AminocxAlkylPhosphonates Giulia Cabella, Giancarlo ... X= Ph21C'CH2NH OH ga X = CH.jCPhHOH a Compounds 2e ... when employing le instead of camphor and ketopinic acid la must depends ...
Rhodococcus opacus R7 was isolated from a soil contaminated with polycyclic aromatic hydrocarbons... more Rhodococcus opacus R7 was isolated from a soil contaminated with polycyclic aromatic hydrocarbons for its ability to grow on naphthalene. The strain was also able to degrade o-xylene, the isomer of xylenes most recalcitrant to microbial degradation. The catabolic pathways for naphthalene and o-xylene were investigated by identification of metabolites in R. opacus R7 cultures performed with the two hydrocarbons and by evaluation of some enzymes involved in the metabolism of these compounds. 1,2-Dihydro-1,2-dihydroxynaphthalene, salicylic and gentisic acids were identified as metabolites in cultures exposed to naphthalene. This suggests that the degradation occurs through the dioxygenation of the aromatic ring with the formation of 1,2-dihydro-1,2-dihydroxynaphthalene, dehydrogenated to the corresponding 1,2-dihydroxy derivative which is further oxidized to salicylic acid, a key intermediate of naphthalene metabolism; this compound is converted to gentisic acid cleaved by a gentisate 1,2-dioxygenase. From R. opacus R7 cultures supplied with o-xylene, 2,3-dimethylphenol and 3,4-dimethylcatechol were observed. The pathway of o-xylene involves the monooxygenation of the benzene nucleus leading to dimethylphenol which is further metabolised to 3,4-dimethylcatechol, followed by a meta cleavage reaction, catalyzed by the catechol 2,3-dioxygenase. R. opacus R7 is the first strain thus far described both in Gram-negative and Gram-positive bacteria which has the ability to degrade both a polycyclic aromatic hydrocarbon such as naphthalene and a monocyclic aromatic hydrocarbon such as o-xylene.
We developed biocatalysts carrying naphthalene dioxygenase and dihydrodiol dehydrogenase genes cl... more We developed biocatalysts carrying naphthalene dioxygenase and dihydrodiol dehydrogenase genes cloned from plasmid pN3 of Pseudomonas fluoresceins N3 involved in naphthalene degradation, as an alternative approach to the production of hydroxylated compounds by chemical synthesis. Naphthalene dioxygenase is responsible for hydroxylation of the hydrocarbon into the corresponding 1,2-dihydro-1,2-dihydroxy derivative and dihydrodiol dehydrogenase is involved in the subsequent transformation into the 1,2-dihydroxy derivative. The first reaction strictly requires the presence of oxygen, essential for the dioxygenation reaction, while the second one can also be performed in anaerobic conditions that are optimal to avoid the easy oxidation of bioconversion products. Consequently, we constructed biocatalysts carrying the genes responsible for the biotransformation of hydrocarbons, inducible under aerobic and anaerobic conditions. We cloned the dioxygenase gene under its promoter, inducible by salicylic acid and the dihydrodiol dehydrogenase under the Pnar promoter of Escherichia coli, inducible by nitrate, in a nitrogen atmosphere, in order to develop biological systems with the possibility of controlling the expression of the cloned genes by the shift from aerobic to anaerobic conditions. Bioconversion experiments performed in aerobic conditions showed dihydrodiol production and dehydrogenase repression; as soon as cultures were switched to nitrogen, dihydrodiol dehydrogenation with an efficient production of 1,2-dihydroxyderivatives was observed.
The electroreductive pathway to phenol glucosidation, recently introduced by our research group, ... more The electroreductive pathway to phenol glucosidation, recently introduced by our research group, is analysed here in detail for both mechanism elucidation and choice of operating conditions. Preparative electrosyntheses were carried out on model substrates, varying ...
Naphthalene dioxygenase, a key enzyme in the dihydroxylation of naphthalene, is encoded by the pl... more Naphthalene dioxygenase, a key enzyme in the dihydroxylation of naphthalene, is encoded by the plasmid pN3, responsible for naphthalene metabolism in Pseudomonas fluorescens N3. The naphthalene dioxygenase, including all the sequences for its expression and the regulatory region, has been localized on the 4.3-kb HindIII-ClaI fragment and on the 3.5-kb HindIII fragment of the plasmid pN3, by Southern analysis using as probes nahA and nahR genes, the homologous genes of the plasmid NAH7 from Pseudomonas putida G7. We cloned in Escherichia coli JM109 the dioxygenase gene and its regulatory region and developed an efficient bacterial system inducible by salicylic acid, able to produce dihydrodiols. E. coli containing recombinant plasmids carrying the dioxygenase gene were analysed for their potential as a biocatalytic tool to produce dihydrodiols from different naphthalenes with the substituent on the aromatic ring at the alpha or beta position. The dihydrodiols, identified by HPLC (hig...
... Silvana Bernasconi a , Fulvia Orsini a , Guido Sello Corresponding Author Contact Information... more ... Silvana Bernasconi a , Fulvia Orsini a , Guido Sello Corresponding Author Contact Information , E-mail The Corresponding Author , a , Andrea Colmegna b , Enrica Galli b and Giuseppina ... 4. F. Beltrametti, AM Marconi, G. Bestetti, C. Colombo, E. Galli, M. Ruzzi and E. Zennaro. ...
... 2, pp. 105 to 118, 1989 0898-5529]89 $3.00+.00 Printed in Great Britain Pergamon Press plc Re... more ... 2, pp. 105 to 118, 1989 0898-5529]89 $3.00+.00 Printed in Great Britain Pergamon Press plc Residual Charges On Atoms In Organic Structures: Molecules Containing Charged and Backdonating Atoms Luca Baumer, Giordano Sala and Guido Sello* Dipartimento di Chimica ...
... All rights reserved PH: S00404020(96)005583 00404020 96 15.00 + 0.00 Reactivity of Glucosyl R... more ... All rights reserved PH: S00404020(96)005583 00404020 96 15.00 + 0.00 Reactivity of Glucosyl Radical in the Presence of Phenols Angelo Alberti, +a Maria A. Delta Bona, a Dante Macciantelli,a Francesca Pelizzoni,b Guido Sello,b ... Larkin, JP; Norman, ROCJ Chem. Soc. ...
The use of two oxidoreductases (an aldoketo reductase from Escherichia coli JM109 and an alcohol ... more The use of two oxidoreductases (an aldoketo reductase from Escherichia coli JM109 and an alcohol dehydrogenase from Lactobacillus brevis) has demonstrated that it is possible to prepare enatiomerically pure diols in a one-pot operation. The reactions were applied to the synthesis of (1R)-1-[3-(hydroxymethyl)phenyl]ethanol and (1S)-1-phenylethane-1,2-diol, using a two-step procedure. The yield is nearly quantitative and the enantiomeric purity is greater
... Alkylation of Chiral Phosphonoglycine Equivalents: Asymmetric Synthesis of Diethyl AminocxAlk... more ... Alkylation of Chiral Phosphonoglycine Equivalents: Asymmetric Synthesis of Diethyl AminocxAlkylPhosphonates Giulia Cabella, Giancarlo ... X= Ph21C'CH2NH OH ga X = CH.jCPhHOH a Compounds 2e ... when employing le instead of camphor and ketopinic acid la must depends ...
Rhodococcus opacus R7 was isolated from a soil contaminated with polycyclic aromatic hydrocarbons... more Rhodococcus opacus R7 was isolated from a soil contaminated with polycyclic aromatic hydrocarbons for its ability to grow on naphthalene. The strain was also able to degrade o-xylene, the isomer of xylenes most recalcitrant to microbial degradation. The catabolic pathways for naphthalene and o-xylene were investigated by identification of metabolites in R. opacus R7 cultures performed with the two hydrocarbons and by evaluation of some enzymes involved in the metabolism of these compounds. 1,2-Dihydro-1,2-dihydroxynaphthalene, salicylic and gentisic acids were identified as metabolites in cultures exposed to naphthalene. This suggests that the degradation occurs through the dioxygenation of the aromatic ring with the formation of 1,2-dihydro-1,2-dihydroxynaphthalene, dehydrogenated to the corresponding 1,2-dihydroxy derivative which is further oxidized to salicylic acid, a key intermediate of naphthalene metabolism; this compound is converted to gentisic acid cleaved by a gentisate 1,2-dioxygenase. From R. opacus R7 cultures supplied with o-xylene, 2,3-dimethylphenol and 3,4-dimethylcatechol were observed. The pathway of o-xylene involves the monooxygenation of the benzene nucleus leading to dimethylphenol which is further metabolised to 3,4-dimethylcatechol, followed by a meta cleavage reaction, catalyzed by the catechol 2,3-dioxygenase. R. opacus R7 is the first strain thus far described both in Gram-negative and Gram-positive bacteria which has the ability to degrade both a polycyclic aromatic hydrocarbon such as naphthalene and a monocyclic aromatic hydrocarbon such as o-xylene.
We developed biocatalysts carrying naphthalene dioxygenase and dihydrodiol dehydrogenase genes cl... more We developed biocatalysts carrying naphthalene dioxygenase and dihydrodiol dehydrogenase genes cloned from plasmid pN3 of Pseudomonas fluoresceins N3 involved in naphthalene degradation, as an alternative approach to the production of hydroxylated compounds by chemical synthesis. Naphthalene dioxygenase is responsible for hydroxylation of the hydrocarbon into the corresponding 1,2-dihydro-1,2-dihydroxy derivative and dihydrodiol dehydrogenase is involved in the subsequent transformation into the 1,2-dihydroxy derivative. The first reaction strictly requires the presence of oxygen, essential for the dioxygenation reaction, while the second one can also be performed in anaerobic conditions that are optimal to avoid the easy oxidation of bioconversion products. Consequently, we constructed biocatalysts carrying the genes responsible for the biotransformation of hydrocarbons, inducible under aerobic and anaerobic conditions. We cloned the dioxygenase gene under its promoter, inducible by salicylic acid and the dihydrodiol dehydrogenase under the Pnar promoter of Escherichia coli, inducible by nitrate, in a nitrogen atmosphere, in order to develop biological systems with the possibility of controlling the expression of the cloned genes by the shift from aerobic to anaerobic conditions. Bioconversion experiments performed in aerobic conditions showed dihydrodiol production and dehydrogenase repression; as soon as cultures were switched to nitrogen, dihydrodiol dehydrogenation with an efficient production of 1,2-dihydroxyderivatives was observed.
The electroreductive pathway to phenol glucosidation, recently introduced by our research group, ... more The electroreductive pathway to phenol glucosidation, recently introduced by our research group, is analysed here in detail for both mechanism elucidation and choice of operating conditions. Preparative electrosyntheses were carried out on model substrates, varying ...
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