Microbial Models of Mammalian Metabolism: Aromatic Hydroxylation of Isomeric Xylenes

Smith, Robert V.; Humphrey, David W.; Engel, Kenneth O.; Rosazza, John P. N.

doi:10.1128/aem.31.3.448-449.1976

Cited by 12 publications

(5 citation statements)

References 8 publications

(8 reference statements)

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“…The aromatic substrates also represented the aromatic portions of numerous chemical entities of environmental importance and of drugs. Details of these experiments have been reviewed (2,3,32). In general, the degree of parallelism was high.…”

Section: Aromatic Hybroxylationsmentioning

confidence: 99%

Microbial Models of Mammalian Metabolism

Smith¹,

Rosazza²

1983

J. Nat. Prod.

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A solid basis for the M4-approach has been developed over the past 10 years. Recent examples of the production of difficult-to-synthesize mammalian metabolites through microbial transformations attest to the utility of the methodology. There is, however, much more to be done. Model studies should be conducted to test parallels between microbial and mammalian S- and N-oxidations, O-glucuronidations, and ester and amide hydrolyses. Subsequently, even greater applications of M4- work can be envisioned. We have been pleased to see our colleagues in industry and academia adopt the M4- approach to solve difficult pharmacological and toxicological problems. In large measure, this has been our greatest reward for efforts initially presented before the membership of the American Society of Pharmacognosy in 1973.

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Section: Aromatic Hybroxylationsmentioning

confidence: 99%

Microbial Models of Mammalian Metabolism

Smith¹,

Rosazza²

1983

J. Nat. Prod.

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“…Hence, there is great potential for expanding the substrate range of oxygenases. Furthermore, these oxygenases may be used to mimic mammalian metabolism to screen potential pharmaceutical drugs; hence, they may have use in fate and toxicity studies (Smith et al, 1976;Smith and Posazza, 1974).…”

Section: Introductionmentioning

confidence: 99%

Regiospecific oxidation of naphthalene and fluorene by toluene monooxygenases and engineered toluene 4‐monooxygenases of Pseudomonas mendocina KR1

Tao

Bentley

Wood

2005

Biotech & Bioengineering

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The regiospecific oxidation of the polycyclic aromatic hydrocarbons naphthalene and fluorene was examined with Escherichia coli strains expressing wildtype toluene 4-monooxygenase (T4MO) from Pseudomonas mendocina KR1, toluene para-monooxygenase (TpMO) from Ralstonia pickettii PKO1, toluene ortho-monooxygenase (TOM) from Burkholderia cepacia G4, and toluene/ortho-xylene monooxygenase (ToMO) from P. stutzeri OX1. T4MO oxidized toluene (12.1+/-0.8 nmol/min/mg protein at 109 microM), naphthalene (7.7+/-1.5 nmol/min/mg protein at 5 mM), and fluorene (0.68+/-0.04 nmol/min/mg protein at 0.2 mM) faster than the other wildtype enzymes (2-22-fold) and produced a mixture of 1-naphthol (52%) and 2-naphthol (48%) from naphthalene, which was successively transformed to a mixture of 2,3-, 2,7-, 1,7-, and 2,6-dihydroxynaphthalenes (7%, 10%, 20%, and 63%, respectively). TOM and ToMO made 1,7-dihydroxynaphthalene from 1-naphthol, and ToMO made a mixture of 2,3-, 2,6-, 2,7-, and 1,7-dihydroxynaphthalene (26%, 22%, 1%, and 44%, respectively) from 2-naphthol. TOM had no activity on 2-naphthol, and T4MO had no activity on 1-naphthol. To take advantage of the high activity of wildtype T4MO but to increase its regiospecificity on naphthalene, seven engineered enzymes containing mutations in T4MO alpha hydroxylase TmoA were examined; the selectivity for 2-naphthol by T4MO I100A, I100S, and I100G was enhanced to 88-95%, and the selectivity for 1-naphthol was enhanced to 87% and 99% by T4MO I100L and G103S/A107G, respectively, while high oxidation rates were maintained except for G103S/A107G. Therefore, the regiospecificity for naphthalene oxidation was altered to practically pure 1-naphthol or 2-naphthol. All four wildtype monooxygenases were able to oxidize fluorene to different monohydroxylated products; T4MO oxidized fluorene successively to 3-hydroxyfluorene and 3,6-dihydroxyfluorene, which was confirmed by gas chromatography-mass spectrometry and 1H nuclear magnetic resonance analysis. TOM and its variant TomA3 V106A oxidize fluorene to a mixture of 1-, 2-, 3-, and 4-hydroxyfluorene. This is the first report of using enzymes to synthesize 1-, 3-, and 4-hydroxyfluorene, and 3,6-dihydroxyfluorene from fluorene as well as 2-naphthol and 2,6-dihydroxynaphthalene from naphthalene.

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“…Mixedfunction oxygenases similar to those occurring in mammals have been found in certain microorganisms (9; R. V. Smith and J. P. Rosazza, in J. P. Rosazza, ed., Microbial Transformations ofPhysiologically Active Compounds, in press). This is the apparent basis for parallel patterns of aromatic hydroxylation observed with 15 model substrates metabolized by 11 microorganisms (12,13). Similar patterns in aromatic hydroxylations of model substrates such as biphenyl by microorganisms typified by Cunninghamella echinulata ATCC 9244 clearly indicate similarities between fungal and mammalian monooxygenase activities (11).…”

mentioning

confidence: 68%

“…It was hypothesized that the rates and extents of cleavage of these substrates by microorganisms would parallel those observed for the same and similar substrates in mammalian preparations. This, in turn, would extend the concept of microbial models of mammalian metabolism to 0-dealkylation as a reaction type as has been accomplished with aromatic hydroxylation (12,13).…”

mentioning

confidence: 99%

Microbial models of mammalian metabolism: O-dealkylation of para-alkoxybiphenyls

Smith¹,

Milton²,

Davis³

1982

Appl Environ Microbiol

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The potential of selected microorganisms to O-dealkylate alkyl aryl ethers in a manner analogous to mammalian systems has been studied. A total of 45 fungi and actinomycetes were screened for their ability to O-demethylate 4-methoxybiphenyl. Of the 20 organisms found to actively metabolize this substrate, 5 were chosen for additional study. Incubation with a series of five homologous 4-alkoxybiphenyls, 4-methoxy-, 4-ethoxy, 4-(1-propoxy)-, 4-(2-propoxy)-, and 4-(1-butoxy)biphenyl, revealed that all were O-dealkylated by Aspergillus flavus ATCC 24741. With Triton X-100 as a solubilizing agent, the relative rates and extent of O-dealkylation of the 4-alkoxybiphenyls, were studied with A. flavus. The methoxy and ethoxy dervatives were dealkylated in more than 90% yield after 72 h of incubation, while the higher homologs were cleaved to the extent of only about 10%. An analogous pattern of O-dealkylation has been reported in mammalian systems.

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Microbial Models of Mammalian Metabolism: Aromatic Hydroxylation of Isomeric Xylenes

Cited by 12 publications

References 8 publications

Microbial Models of Mammalian Metabolism

Microbial Models of Mammalian Metabolism

Regiospecific oxidation of naphthalene and fluorene by toluene monooxygenases and engineered toluene 4‐monooxygenases of Pseudomonas mendocina KR1

Microbial models of mammalian metabolism: O-dealkylation of para-alkoxybiphenyls

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