Reduction Of Benzoate Research Articles

A pH-dependent shift of redox cofactor specificity in a benzyl alcohol dehydrogenase of aromatoleum aromaticum EbN1

We characterise a reversible bacterial zinc-containing benzyl alcohol dehydrogenase (BaDH) accepting either NAD+ or NADP+ as a redox cofactor. Remarkably, its redox cofactor specificity is pH-dependent with the phosphorylated cofactors favored at lower and the dephospho-forms at higher pH. BaDH also shows different steady-state kinetic behavior with the two cofactor forms. From a structural model, the pH-dependent shift may affect the charge of a histidine in the 2′-phosphate-binding pocket of the redox cofactor binding site. The enzyme is phylogenetically affiliated to a new subbranch of the Zn-containing alcohol dehydrogenases, which share this conserved residue. BaDH appears to have some specificity for its substrate, but also turns over many substituted benzyl alcohol and benzaldehyde variants, as well as compounds containing a conjugated C=C double bond with the aldehyde carbonyl group. However, compounds with an sp3-hybridised C next to the alcohol/aldehyde group are not or only weakly turned over. The enzyme appears to contain a Zn in its catalytic site and a mixture of Zn and Fe in its structural metal-binding site. Moreover, we demonstrate the use of BaDH in an enzyme cascade reaction with an acid-reducing tungsten enzyme to reduce benzoate to benzyl alcohol.Key points•Zn-containing BaDH has activity with either NAD+or NADP+at different pH optima.•BaDH converts a broad range of substrates.•BaDH is used in a cascade reaction for the reduction of benzoate to benzyl alcohol.

Characterization of an Aldehyde Oxidoreductase From the Mesophilic Bacterium Aromatoleum aromaticum EbN1, a Member of a New Subfamily of Tungsten-Containing Enzymes.

The biochemical properties of a new tungsten-containing aldehyde oxidoreductase from the mesophilic betaproteobacterium Aromatoleum aromaticum EbN1 (AORAa) are presented in this study. The enzyme was purified from phenylalanine-grown cells of an overexpressing mutant lacking the gene for an aldehyde dehydrogenase normally involved in anaerobic phenylalanine degradation. AORAa catalyzes the oxidation of a broad variety of aldehydes to the respective acids with either viologen dyes or NAD+ as electron acceptors. In contrast to previously known AORs, AORAa is a heterohexameric protein consisting of three different subunits, a large subunit containing the W-cofactor and an Fe-S cluster, a small subunit containing four Fe-S clusters, and a medium subunit containing an FAD cofactor. The presence of the expected cofactors have been confirmed by elemental analysis and spectrophotometric methods. AORAa has a pH optimum of 8.0, a temperature optimum of 40°C and is completely inactive at 50°C. Compared to archaeal AORs, AORAa is remarkably resistant against exposure to air, exhibiting a half-life time of 1 h as purified enzyme and being completely unaffected in cell extracts. Kinetic parameters of AORAa have been obtained for the oxidation of one aliphatic and two aromatic aldehydes, resulting in about twofold higher kcat values with benzyl viologen than with NAD+ as electron acceptor. Finally, we obtained evidence that AORAa is also catalyzing the reverse reaction, reduction of benzoate to benzaldehyde, albeit at very low rates and under conditions strongly favoring acid reduction, e.g., low pH and using Ti(III) citrate as electron donor of very low redox potential. AORAa appears to be a prototype of a new subfamily of bacterial AOR-like tungsten-enzymes, which differ from the previously known archaeal AORs mostly by their multi-subunit composition, their low sensitivity against oxygen, and the ability to use NAD+ as electron acceptor.

Total synthesis of honokiol by selective samarium-mediated allylic benzoate reduction

The total synthesis of the biologically relevant compound honokiol has been completed featuring a samarium-mediated bis-benzoyl ester reduction to simultaneously install both allyl substituents found in the natural product. This reaction was performed after a Suzuki coupling was used to generate the biphenyl core, thereby avoiding problems associated with the acidity of these allyl groups and their propensity to isomerize. In this way, the synthesis of honokiol could be completed in 4 steps and 42% overall yield.

Comparative proteomic analysis reveals mechanistic insights into Pseudomonas putida F1 growth on benzoate and citrate

Pseudomonas species are capable to proliferate under diverse environmental conditions and thus have a significant bioremediation potential. To enhance our understanding of their metabolic versatility, this study explores the changes in the proteome and physiology of Pseudomonas putida F1 resulting from its growth on benzoate, a moderate toxic compound that can be catabolized, and citrate, a carbon source that is assimilated through central metabolic pathways. A series of repetitive batch cultivations were performed to ensure a complete adaptation of the bacteria to each of these contrasting carbon sources. After several growth cycles, cell growth stabilized at the maximum level and exhibited a reproducible growth profile. The specific growth rates measured for benzoate (1.01 ± 0.11 h-1) and citrate (1.11 ± 0.12 h-1) were similar, while a higher yield was observed for benzoate (0.6 and 0.3 g cell mass per g of benzoate and citrate, respectively), reflecting the different degrees of carbon reduction in the two substrates. Comparative proteomic analysis revealed an enrichment of several oxygenases/dehydrogenases in benzoate-grown cells, indicative of the higher carbon reduction of benzoate. Moreover, the upregulation of all 14 proteins implicated in benzoate degradation via the catechol ortho-cleavage pathway was observed, while several stress-response proteins were increased to aid cells to cope with benzoate toxicity. Unexpectedly, citrate posed more challenges than benzoate in the maintenance of pH homeostasis, as indicated by the enhancement of the Na+/H+ antiporter and carbonic anhydrase. The study provides important mechanistic insights into Pseudomonas adaptation to varying carbon sources that are of great relevance to bioremediation efforts.

Voltammetric Investigations of the Fries Rearrangement in an Ionic Liquid

The electrochemical behavior of phenyl benzoate (PB) in the neutral AlCl3 : 1-ethyl-3-methylimidazolium chloride ionic liquid has been studied. Addition of HfCl4 to phenyl benzoate in this medium produces a positive potential shift for the phenyl benzoate reduction process. Heating the solution to 80oC for 30 hours gives 4-hydroxybenzophenone as the major product. Cyclic voltammetric studies show that HfCl4 reacts with the ionic liquid to produce relatively small amounts of Al2Cl7-, so that HfCl4 is still the principal Lewis acid in this system. Comparison studies using added AlCl3 in place of HfCl4 show similar behavior, with a somewhat different potential shift for the AlCl3 : PB interaction.

Electrochemical Studies of the Fries Rearrangement in Ionic Liquids

The Fries rearrangement of phenyl benzoate has been studied in the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI BF4). Addition of the proton acid triflic acid was found to shift the reduction potential of phenyl benzoate from -2.0V to -1.1V vs Ag/AgCl, implying protonation of phenyl benzoate by triflic acid. After 1 day, however, the phenyl benzoate reduction potential shifted back to its original value, suggesting that triflic acid slowly reacts with the ionic liquid.

Catalytic reduction of benzoate esters and lactones in the presence of PhMeSiH2and a titanocene-based catalyst

PhMeSiH2reduces ethyl benzoate in the presence of a Cp2TiMe2(Cp = η5-cyclopentadienyl) catalyst to give PhMeSi(OEt)(OCH2Ph) (1). Small to moderate amounts of toluene are also produced, depending on the reaction conditions. Under 40 psi of H2the same reaction gives quantitative reduction of the ester to toluene. PhCHO is reduced, under the same conditions as the ester, to a mixture of PhMeSi(OCH2Ph)2and toluene in proportions similar to that observed with the ester. A stoichiometric reaction of PhMeSiH2, PhCOOEt, and Cp2TiMe2resulted in the formation of known [Cp2Ti(OEt)]2(2) in 75% isolated yield. A mechanism is proposed in which the C=O of the ester inserts into a Ti–H bond. A Ti-mediated transfer of the ethoxy group from the resulting (α-ethoxy)benzyloxytitanium intermediate to silicon produces PhMeSi(OEt)H and PhCHO. 1 is generated via hydrosilation of PhCHO by PhMeSi(OEt)H. Both β- and γ-butyrolactones react with PhMeSiH2in the presence of a catalytic amount of Cp2TiMe2to produce copolymers -[O-PhMeSi-O(CH2)3CHR]n- (R = H, 3; R = Me, 4) (Mw[Formula: see text] 1 × 103; Mw/Mn[Formula: see text] 1.3). A mechanism analogous to that proposed for the ethyl benzoate reduction is proposed. A reaction of PhMeSiH2and γ-butyrolactone with a stoichiometric amount of Cp2TiMe2in the presence of tetrahydofuran (THF) produces Cp2Ti(µ-H)(µ-η1,η5-C5H4)Ti(OC4H8)Cp(5) (65% isolated yield) whose structure is determined by X-ray crystallography.Key words: hydrosilation, esters, lactones, titanocene, catalysis.

Chiral Preparation of C2-Symmetric 4-Cyclopentene-1,3-diol

Optically pure C2 -symmetric 4-cyclopentene-1,3-diol has been prepared in both enantiomeric forms from racemic (3aS*,4R*,7S*,7aS*)-3a,4,7,7a-tetrahydro-4,7-methano-1H-inden-1-one by employing lipase-mediated kinetic resolution as the key step. As a result, the known (3aS*,4R*,7S*,7aS*)-3a,4,7,7a-tetrahydro-4,7-methano-1H-inden-1-one is transformed into (1′S*,3′S*,3′aR*,4′S*,7′R*,7′aS*)- 2′,3′,3′a,4′,7′,7′a-hexahydro-3′-hydroxy-4′,7′-methano-1′H-inden-1′-yl benzoate, via stereo- and regioselective hydride reduction of epoxy ketone and sequential benzoylation, which is resolved under transesterification conditions in the presence of lipase. The hydride reduction of benzoate and acetate gives the corresponding chiral diols, which are further transformed into both enantiomers of C2 -symmetric 4-cyclopentene-1,3-diol via a retro-Diels-Alder reaction.

Energetics of product formation during anaerobic degradation of phthalate isomers and benzoate

Methanogenic enrichment cultures grown on phthalate, isophthalate and terephthalate were incubated with the corresponding phthalate isomer on which they were grown, and a mixture of benzoate and the phthalate isomer. All cultures were incubated with bromoethanosulfonate to inactivate the methanogens in the mixed culture. Thus, product formation during fermentation of the aromatic substrates could be studied. It was found that reduction equivalents generated during oxidation of the aromatic substrates to acetate were incorporated in benzoate under formation of carboxycyclohexane. During fermentation of the phthalate isomers, small amounts of benzoate were detected, suggesting that the initial step in the anaerobic degradation of the phthalate isomers is decarboxylation to benzoate. Gibbs free energy analyses indicated that during degradation of the phthalate isomers, benzoate, carboxycyclohexane, acetate and molecular hydrogen accumulated in such amounts that both the reduction and oxidation of benzoate yielded a constant and comparable amount of energy of approximately 30 kJ mol−1. Based on these observations it is suggested that within narrow energetic limits, oxidation and reduction of benzoate may proceed simultaneously. Whether this is controlled by the Gibbs free energy change for carboxycyclohexane oxidation remains unclear.

Energetics of product formation during anaerobic degradation of phthalate isomers and benzoate

Methanogenic enrichment cultures grown on phthalate, isophthalate and terephthalate were incubated with the corresponding phthalate isomer on which they were grown, and a mixture of benzoate and the phthalate isomer. All cultures were incubated with bromoethanosulfonate to inactivate the methanogens in the mixed culture. Thus, product formation during fermentation of the aromatic substrates could be studied. It was found that reduction equivalents generated during oxidation of the aromatic substrates to acetate were incorporated in benzoate under formation of carboxycyclohexane. During fermentation of the phthalate isomers, small amounts of benzoate were detected, suggesting that the initial step in the anaerobic degradation of the phthalate isomers is decarboxylation to benzoate. Gibbs free energy analyses indicated that during degradation of the phthalate isomers, benzoate, carboxycyclohexane, acetate and molecular hydrogen accumulated in such amounts that both the reduction and oxidation of benzoate yielded a constant and comparable amount of energy of approximately 30 kJ mol −1. Based on these observations it is suggested that within narrow energetic limits, oxidation and reduction of benzoate may proceed simultaneously. Whether this is controlled by the Gibbs free energy change for carboxycyclohexane oxidation remains unclear.

Reduction of 3-chlorobenzoate, 3-bromobenzoate, and benzoate to corresponding alcohols by Desulfomicrobium escambiense, isolated from a 3-chlorobenzoate-dechlorinating coculture.

An anaerobic bacterial coculture which dechlorinated 3-chlorobenzoate (3CB) to benzoate was obtained by single-colony isolation from an anaerobic bacterial consortium which completely degraded 3CB in defined medium. Of 29 additional halogenated aromatic compounds tested, the coculture removed the meta halogen from 2,3- and 2,5-dichlorobenzoate, 3-bromobenzoate (3BB), 5-chlorovanillate (5CV), and 3-chloro-4-hydroxybenzoate. Dechlorinating activity in the coculture required the presence of pyruvate. 5CV was also O-demethoxylated. The coculture contained two cell types: a short, straight gram-negative rod and a long, thin, curved gram-positive rod. The short rod, Desulfomicrobium escambiense, was recently isolated and identified as a new sulfate-reducing bacterial species (B. R. Sharak Genthner, S. D. Friedman, and R. Devereux, Int. J. Syst. Bacteriol. 47:889-892, 1997; B. R. Sharak Genthner, G. Mundfrom, and R. Devereux, Arch. Microbiol. 161:215-219, 1994). D. escambiense did not dehalogenate any of the compounds dehalogenated by the coculture, nor dit it O-demethoxylate 5CV or vanillate. However, D. escambiense reduced 3CB, EBB, and benzoate to their respective benzyl alcohols. Reduction to alcohols required the presence of pyruvate, which was transformed to acetate, lactate, and succinate in the presence of absence of 3CB, 3BB, or benzoate. Alcohol formation did not occur in pyruvate-sulfate medium. Under these conditions, sulfate was preferentially reduced. Other electron donors that supported the growth of D. escambiense during sulfate reduction did not support benzoate reduction to benzyl alcohol.

Products of enzymatic reduction of benzoyl-CoA, a key reaction in anaerobic aromatic metabolism.

Benzoyl-coenzyme A is the most common central intermediate of anaerobic aromatic metabolism. Studies with whole cells of different bacteria and in vitro had shown that benzoyl-CoA is reduced to alicyclic compounds, possibly via cyclohexadiene intermediates. This reaction is considered a 'biological Birch reduction'. We have elucidated by NMR techniques the structures of six products of [ring-13C6]benzoate reduction. The reaction is catalyzed by extracts from cells of a denitrifying Pseudomonas strain K172 anaerobically grown with benzoate and nitrate as sole carbon and energy sources. The assay mixture contained [ring-13C6]benzoate plus traces of [U-14C]benzoate, Mg2+, ATP, coenzyme A (CoA), and Ti(III) as reductant. The use of the multiply 13C-labelled precursor increases the sensitivity of NMR detection and allows the analysis of crude product mixtures by two-dimensional coherence transfer procedures such as total correlation 13C-NMR spectroscopy and 13C-filtered 1H-NMR spectroscopy. The time course of product formation is consistent with the following order of events. Benzoyl-CoA is formed from benzoate via benzoate-CoA ligase. The first ring reduction product observed is cyclohex-1,5-diene-1-carboxyl-CoA. The next intermediate is 6-hydroxycyclohex-1-ene-1-carboxyl-CoA which is derived from the diene by addition of water. Part of the diene seems to be reduced to cyclohex-1-ene-1-carboxyl-CoA which becomes hydrated to trans-2-hydroxycyclohexane-1-carboxyl-CoA; these two intermediates may be side products in vitro. The first non-cyclic intermediate formed by beta-oxidation is 3-hydroxypimelyl-CoA. This aliphatic C7 dicarboxylic acid is proposed to be oxidized via glutaryl-CoA and crotonyl-CoA to three molecules of acetyl-CoA and one molecule of CO2. A similar product pattern was observed in the benzoate-degrading phototrophic bacterium Rhodopseudomonas palustris. This indicates that the enzymatic reduction of benzoyl-CoA may be mechanistically similar in different anaerobes.

Purification and characterization of aromatic acid reductase from Nocardia asteroides JCM 3016.

Aromatic acid reductase (aryl-aldehyde dehydrogenase, EC 1.2.1.30) was purified to electrophoretic homogeneity from Nocardia asteroides JCM 3016. The enzyme was a monomeric protein with a molecular weight of 152, 000. The enzyme absolutely required ATP, NADPH, and MgCl2 for the reduction of benzoate to benzaldehyde. In the overall reaction, benzaldehyde, AMP, and NADP+ were stoichiometrically formed from benzoate, ATP and NADPH, respectively. The purified enzyme catalyzed the reduction of benzoyl adenosine 5'-monophosphate (bzAMP), which is the intermediate formed from benzoate and ATP. The temperature dependence of the benzoate- and bzAMP-reducing activities agreed exactly, and the same Km for NADPH was obtained by the steady state kinetics of both reactions. These results suggest that the overall reduction of benzoate proceeds via bzAMP, and that the ATP-dependent adenylation of benzoate and the reduction of bzAMP are catalyzed by one enzyme. The enzyme was fairly specific for meta-substituted benzoates.

Reductive transformation of benzoate by Nocardia asteroides and Hormoconis resinae

A variety of substituted aromatic acids were reduced to the corresponding alcohols by Nocardia asteroides JCM3016 under aerobic conditions. An isolated mold, Hormoconis resinae F328, could also reductively transform benzoate, the erythro isomer of (1R, 2S)-1-phenyl-1,2-propanediol being yielded as well as benzyl alcohol. C-1 of the diol was found to be derived from the α-carbon of benzoate by 13C-NMR analysis. The acyloin condensation between pyruvate and benzaldehyde formed from benzoate is assumed to participate in the diol formation. An ATP-dependent and NADPH-linked benzoate reductase (EC 1.2.1.30) and an NADPH-linked benzaldehyde reductase (EC 1.1.1.91) were demonstrated to participate in the benzoate reduction in both N. asteroides JCM 3016 and H. resinae F328.

Microbial Reduction of Benzoate to Benzyl Alcohol

Microbial Reduction of Benzoate to Benzyl Alcohol Get access Nobuo Kato, Nobuo Kato Department of Environmental Chemistry and Technology, Tottori University, Tottori 680, Japan Search for other works by this author on: Oxford Academic Google Scholar Hisatoshi Konishi, Hisatoshi Konishi Department of Environmental Chemistry and Technology, Tottori University, Tottori 680, Japan Search for other works by this author on: Oxford Academic Google Scholar Kenji Uda, Kenji Uda Department of Environmental Chemistry and Technology, Tottori University, Tottori 680, Japan Search for other works by this author on: Oxford Academic Google Scholar Masayuki Shimao, Masayuki Shimao Department of Environmental Chemistry and Technology, Tottori University, Tottori 680, Japan Search for other works by this author on: Oxford Academic Google Scholar Chikahiro Sakazawa Chikahiro Sakazawa Department of Environmental Chemistry and Technology, Tottori University, Tottori 680, Japan Search for other works by this author on: Oxford Academic Google Scholar Agricultural and Biological Chemistry, Volume 52, Issue 7, 1 July 1988, Pages 1885–1886, https://doi.org/10.1080/00021369.1988.10868949 Published: 01 July 1988 Article history Received: 07 April 1988 Published: 01 July 1988

Microbial reduction of benzoate to benzyl alcohol.

Microbial reduction of benzoate to benzyl alcohol.

Microbial Metabolism of Cyclic Hydrocarbons and Related Compounds

The utilization of alicyclic hydrocarbons by microorganisms will be reviewed as well as substituted and unsubstituted cyclic hydrocarbons. The topics discussed include: the enzymes involved in biodegradation of cycloparaffins and probable intemediates involved in the metabolism of cycloparaffinic hydrocarbons; the role of cooxidation in the utilization of cycloalkanes as well as the accumulation of intermediates of cycloalkane metabolism via this technique; the oxidase (hydroxylase) involved in cycloalkane biodegradation; the aromatization of the cycloalkane ring in the aerobic degradation of cyclohexane and the reduction of benzoate in anaerobic metabolism of heterotrophs and photosynthetic bacteria; the incorporation of cycloalkanes with n-alkyl side chains into cellular lipids; and the biodegradation of terpenes and related compounds by microorganisms.

Polarographic Reduction of Benzoate in Acetonitrile

AbstractThe polarographic wave observed for acetonitrile solutions of benzoic acid is due to reduction of the acid proton; the apparent diffusion current constant for the wave increases with concentration of benzoic acid as expected for the reduction of the acidic proton of a slightly dissociated acid. No wave was observed for ethyl benzoate.