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Janusz Jurczak - One of the best experts on this subject based on the ideXlab platform.
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sterically modified chiral salen cr iii complexes efficient catalysts for the oxo diels alder reaction between glyoxylates and cyclohexa 1 3 diene
Synlett, 2006Co-Authors: Wojciech Chaadaj, Piotr Kwiatkowski, Janusz JurczakAbstract:A group of chiral [(salen)Cr(III)] + BF 4 - complexes, with enhanced steric hindrance in 3,3'-positions of salicylidene moiety, has been synthesized and applied for the oxo-Diels-Alder reaction of alkyl glyoxylates with cyclohexa-1,3-diene. A readily accessible complex that bears bulky adamanthyl substituents revealed its potential, leading to the cycloadducts with excellent selectivity (up to endolexo 99:1, 98% ee), considerably better than the classic Jacob-sen catalyst.
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enantioselective 4 2 cycloaddition of buta 1 3 dienes to alkyl glyoxylates catalyzed by the chiral salen chromium iii complex
Advanced Synthesis & Catalysis, 2003Co-Authors: Piotr Kwiatkowski, Monika Asztemborska, Jeanclaude Caille, Janusz JurczakAbstract:Thermal and high-pressure [4+2] cycloadditions of buta-1,3-diene (3), cyclohexa-1,3-diene (5), and 2,3-dimethylbuta-1,3-diene (6) to alkyl glyoxylates of type 2 ( Rn-Bu, i-Pr, t-Bu), catalyzed by chromium complex (R,R)-1, leading to the corresponding cycloadducts 4, 7 and 8 with relatively high enantioselectivity, are described.
Matthias Boll - One of the best experts on this subject based on the ideXlab platform.
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Promiscuous Defluorinating Enoyl-CoA Hydratases/Hydrolases Allow for Complete Anaerobic Degradation of 2-Fluorobenzoate
Frontiers Media S.A., 2017Co-Authors: Oliver Tiedt, Mario Mergelsberg, Wolfgang Eisenreich, Matthias BollAbstract:Biodegradation of the environmentally hazardous fluoroaromatics has mainly been associated with oxygenase-dependent defluorination reactions. Only very recently a novel mode of oxygen-independent defluorination was identified for the complete degradation of para-substituted fluoroaromatics in the denitrifying Thauera aromatica: a promiscuous class I benzoyl-coenzyme A (BzCoA) reductase (BCR) catalyzed the ATP-dependent defluorination of 4-F-BzCoA to BzCoA. Here, we studied the unknown enzymatic defluorination during the complete degradation of 2-F-benzoate to CO2 and HF. We demonstrate that after activation of 2-F-benzoate by a promiscuous AMP-forming benzoate-CoA ligase, the 2-F-BzCoA formed is subsequently dearomatized by BCR to a mixture of 2-F- and 6-F-cyclohexa-1,5-diene-1-carboxyl-CoA (2-F-/6-F-1,5-dienoyl-CoA). This finding indicates that BCR is not involved in C–F-bond cleavage during growth with 2-F-benzoate. Instead, we identified defluorination of the two isomers by enoyl-CoA hydratases/hydrolases involved in down-stream reactions of the BzCoA degradation pathway. (i) The 1,5-dienoyl-CoA hydratase hydrated the F-1,5-dienoyl-CoA isomers to a mixture of the stable 2-F-6-OH-1-enoyl-CoA and the unstable α-fluorohydrin 6-F-6-OH-1-enoyl-CoA; the latter spontaneously decomposed to HF and 6-oxo-cyclohex-1-enoyl-CoA (6-oxo-1-enoyl-CoA), a common intermediate of the BzCoA degradation pathway. (ii) 6-Oxo-1-enoyl-CoA hydrolase/hydratase catalyzed the defluorination of 2-F-6-OH-1-enoyl-CoA to 2-oxo-6-OH-1-enoyl-CoA and HF again via water addition to an F-enoyl-CoA functionality. Based on these in vitro results, we demonstrate a previously overseen capability of 2-F-benzoate degradation for many but not all tested facultatively and obligately anaerobic bacteria that degrade aromatic compounds via the BzCoA degradation pathway. In conclusion, the newly identified enzymatic defluorination by enoyl-CoA hydratases via α-fluorohydrin formation represents an abundant, physiologically relevant principle of enzymatic defluorination
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cyclohexanecarboxyl coenzyme a coa and cyclohex 1 ene 1 carboxyl coa dehydrogenases two enzymes involved in the fermentation of benzoate and crotonate in syntrophus aciditrophicus
Journal of Bacteriology, 2013Co-Authors: Johannes W Kung, Jana Seifert, Martin Von Bergen, Matthias BollAbstract:The strictly anaerobic Syntrophus aciditrophicus is a fermenting deltaproteobacterium that is able to degrade benzoate or crotonate in the presence and in the absence of a hydrogen-consuming partner. During growth in pure culture, both substrates are dismutated to acetate and cyclohexane carboxylate. In this work, the unknown enzymes involved in the late steps of cyclohexane carboxylate formation were studied. Using enzyme assays monitoring the oxidative direction, a cyclohex-1-ene-1-carboxyl-CoA (Ch1CoA)-forming cyclohexanecarboxyl-CoA (ChCoA) dehydrogenase was purified and characterized from S. aciditrophicus and after heterologous expression of its gene in Escherichia coli. In addition, a cyclohexa-1,5-diene-1-carboxyl-CoA (Ch1,5CoA)-forming Ch1CoA dehydrogenase was characterized after purification of the heterologously expressed gene. Both enzymes had a native molecular mass of 150 kDa and were composed of a single, 40- to 45-kDa subunit; both contained flavin adenine dinucleotide (FAD) as a cofactor. While the ChCoA dehydrogenase was competitively inhibited by Ch1CoA in the oxidative direction, Ch1CoA dehydrogenase further converted the product Ch1,5CoA to benzoyl-CoA. The results obtained suggest that Ch1,5CoA is a common intermediate in benzoate and crotonate fermentation that serves as an electron-accepting substrate for the two consecutively operating acyl-CoA dehydrogenases characterized in this work. In the case of benzoate fermentation, Ch1,5CoA is formed by a class II benzoyl-CoA reductase; in the case of crotonate fermentation, Ch1,5CoA is formed by reversing the reactions of the benzoyl-CoA degradation pathway that are also employed during the oxidative (degradative) branch of benzoate fermentation.
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cyclohexanecarboxyl coenzyme a coa and cyclohex 1 ene 1 carboxyl coa dehydrogenases two enzymes involved in the fermentation of benzoate and crotonate in syntrophus aciditrophicus
Journal of Bacteriology, 2013Co-Authors: Johannes W Kung, Jana Seifert, Martin Von Bergen, Matthias BollAbstract:The strictly anaerobic Syntrophus aciditrophicus is a fermenting deltaproteobacterium that is able to degrade benzoate or crotonate in the presence and in the absence of a hydrogen-consuming partner. During growth in pure culture, both substrates are dismutated to acetate and cyclohexane carboxylate. In this work, the unknown enzymes involved in the late steps of cyclohexane carboxylate formation were studied. Using enzyme assays monitoring the oxidative direction, a cyclohex-1-ene-1-carboxyl-CoA (Ch1CoA)-forming cyclohexanecarboxyl-CoA (ChCoA) dehydrogenase was purified and characterized from S. aciditrophicus and after heterologous expression of its gene in Escherichia coli. In addition, a cyclohexa-1,5-diene-1-carboxyl-CoA (Ch1,5CoA)-forming Ch1CoA dehydrogenase was characterized after purification of the heterologously expressed gene. Both enzymes had a native molecular mass of 150 kDa and were composed of a single, 40- to 45-kDa subunit; both contained flavin adenine dinucleotide (FAD) as a cofactor. While the ChCoA dehydrogenase was competitively inhibited by Ch1CoA in the oxidative direction, Ch1CoA dehydrogenase further converted the product Ch1,5CoA to benzoyl-CoA. The results obtained suggest that Ch1,5CoA is a common intermediate in benzoate and crotonate fermentation that serves as an electron-accepting substrate for the two consecutively operating acyl-CoA dehydrogenases characterized in this work. In the case of benzoate fermentation, Ch1,5CoA is formed by a class II benzoyl-CoA reductase; in the case of crotonate fermentation, Ch1,5CoA is formed by reversing the reactions of the benzoyl-CoA degradation pathway that are also employed during the oxidative (degradative) branch of benzoate fermentation.
Johannes W Kung - One of the best experts on this subject based on the ideXlab platform.
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cyclohexanecarboxyl coenzyme a coa and cyclohex 1 ene 1 carboxyl coa dehydrogenases two enzymes involved in the fermentation of benzoate and crotonate in syntrophus aciditrophicus
Journal of Bacteriology, 2013Co-Authors: Johannes W Kung, Jana Seifert, Martin Von Bergen, Matthias BollAbstract:The strictly anaerobic Syntrophus aciditrophicus is a fermenting deltaproteobacterium that is able to degrade benzoate or crotonate in the presence and in the absence of a hydrogen-consuming partner. During growth in pure culture, both substrates are dismutated to acetate and cyclohexane carboxylate. In this work, the unknown enzymes involved in the late steps of cyclohexane carboxylate formation were studied. Using enzyme assays monitoring the oxidative direction, a cyclohex-1-ene-1-carboxyl-CoA (Ch1CoA)-forming cyclohexanecarboxyl-CoA (ChCoA) dehydrogenase was purified and characterized from S. aciditrophicus and after heterologous expression of its gene in Escherichia coli. In addition, a cyclohexa-1,5-diene-1-carboxyl-CoA (Ch1,5CoA)-forming Ch1CoA dehydrogenase was characterized after purification of the heterologously expressed gene. Both enzymes had a native molecular mass of 150 kDa and were composed of a single, 40- to 45-kDa subunit; both contained flavin adenine dinucleotide (FAD) as a cofactor. While the ChCoA dehydrogenase was competitively inhibited by Ch1CoA in the oxidative direction, Ch1CoA dehydrogenase further converted the product Ch1,5CoA to benzoyl-CoA. The results obtained suggest that Ch1,5CoA is a common intermediate in benzoate and crotonate fermentation that serves as an electron-accepting substrate for the two consecutively operating acyl-CoA dehydrogenases characterized in this work. In the case of benzoate fermentation, Ch1,5CoA is formed by a class II benzoyl-CoA reductase; in the case of crotonate fermentation, Ch1,5CoA is formed by reversing the reactions of the benzoyl-CoA degradation pathway that are also employed during the oxidative (degradative) branch of benzoate fermentation.
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cyclohexanecarboxyl coenzyme a coa and cyclohex 1 ene 1 carboxyl coa dehydrogenases two enzymes involved in the fermentation of benzoate and crotonate in syntrophus aciditrophicus
Journal of Bacteriology, 2013Co-Authors: Johannes W Kung, Jana Seifert, Martin Von Bergen, Matthias BollAbstract:The strictly anaerobic Syntrophus aciditrophicus is a fermenting deltaproteobacterium that is able to degrade benzoate or crotonate in the presence and in the absence of a hydrogen-consuming partner. During growth in pure culture, both substrates are dismutated to acetate and cyclohexane carboxylate. In this work, the unknown enzymes involved in the late steps of cyclohexane carboxylate formation were studied. Using enzyme assays monitoring the oxidative direction, a cyclohex-1-ene-1-carboxyl-CoA (Ch1CoA)-forming cyclohexanecarboxyl-CoA (ChCoA) dehydrogenase was purified and characterized from S. aciditrophicus and after heterologous expression of its gene in Escherichia coli. In addition, a cyclohexa-1,5-diene-1-carboxyl-CoA (Ch1,5CoA)-forming Ch1CoA dehydrogenase was characterized after purification of the heterologously expressed gene. Both enzymes had a native molecular mass of 150 kDa and were composed of a single, 40- to 45-kDa subunit; both contained flavin adenine dinucleotide (FAD) as a cofactor. While the ChCoA dehydrogenase was competitively inhibited by Ch1CoA in the oxidative direction, Ch1CoA dehydrogenase further converted the product Ch1,5CoA to benzoyl-CoA. The results obtained suggest that Ch1,5CoA is a common intermediate in benzoate and crotonate fermentation that serves as an electron-accepting substrate for the two consecutively operating acyl-CoA dehydrogenases characterized in this work. In the case of benzoate fermentation, Ch1,5CoA is formed by a class II benzoyl-CoA reductase; in the case of crotonate fermentation, Ch1,5CoA is formed by reversing the reactions of the benzoyl-CoA degradation pathway that are also employed during the oxidative (degradative) branch of benzoate fermentation.
Adelbert Bacher - One of the best experts on this subject based on the ideXlab platform.
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cyclohexa 1 5 diene 1 carboxyl coa hydratase an enzyme involved in anaerobic metabolism of benzoyl coa in the denitrifying bacterium thauera aromatica
FEBS Journal, 1998Co-Authors: Diana Laempe, Wolfgang Eisenreich, Adelbert BacherAbstract:Many aromatic compounds can be metabolized by bacteria under anoxic conditions via benzoyl-CoA as the common intermediate. The central pathway of benzoyl-CoA metabolism is initiated by an ATP-driven reduction of the aromatic ring producing cyclohexa-1,5-diene-1-carboxyl-CoA. The 1,5-dienoyl-CoA intermediate is thought to be transformed to 6-hydroxycyclohex-1-ene-1-carboxyl-CoA by a specific dienoyl-CoA hydratase catalyzing the formal addition of water to one of the double bonds. This dienoyl-CoA hydratase was detected in the denitrifying bacterium Thauera aromatica after anaerobic growth with benzoate. Substrate and product were confirmed and a convenient spectrophotometric assay was developed. The equilibrium concentrations of substrate and product were almost equal. Enzyme activity was induced after anoxic growth with benzoate, in contrast to acetate. The enzyme of 28 kDa was purified from T. aromatica and was found to be highly specific for the cyclic 1,5-dienoyl-CoA. A second 29-kDa enoyl-CoA hydratase acted on crotonyl-CoA; this highly active enoyl-CoA hydratase also acted slowly on cyclohex-1-ene-1-carboxyl-CoA. The regulation of expression of dienoyl-CoA hydratase activity, the kinetic constants, the substrate specificity, and the specific activity of the enzyme in cell extract provide evidence that dienoyl-CoA hydratase is the second enzyme of the central benzoyl-CoA pathway of anaerobic aromatic metabolism in T. aromatica. Extracts of Rhodopseudomonas palustris contained high activity of cyclohex-1-ene-1-carboxyl-CoA hydratase, but no 1,5-dienoyl-CoA hydratase activity. It appears that a variant of the benzoyl-CoA pathway is operating in R. palustris in which hydration of the 1,5-dienoyl-CoA does not take place. Rather, cyclohex-1-ene-1-carboxyl-CoA is hydrated to 2-hydroxycyclohexane-1-carboxyl-CoA.
Jana Seifert - One of the best experts on this subject based on the ideXlab platform.
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cyclohexanecarboxyl coenzyme a coa and cyclohex 1 ene 1 carboxyl coa dehydrogenases two enzymes involved in the fermentation of benzoate and crotonate in syntrophus aciditrophicus
Journal of Bacteriology, 2013Co-Authors: Johannes W Kung, Jana Seifert, Martin Von Bergen, Matthias BollAbstract:The strictly anaerobic Syntrophus aciditrophicus is a fermenting deltaproteobacterium that is able to degrade benzoate or crotonate in the presence and in the absence of a hydrogen-consuming partner. During growth in pure culture, both substrates are dismutated to acetate and cyclohexane carboxylate. In this work, the unknown enzymes involved in the late steps of cyclohexane carboxylate formation were studied. Using enzyme assays monitoring the oxidative direction, a cyclohex-1-ene-1-carboxyl-CoA (Ch1CoA)-forming cyclohexanecarboxyl-CoA (ChCoA) dehydrogenase was purified and characterized from S. aciditrophicus and after heterologous expression of its gene in Escherichia coli. In addition, a cyclohexa-1,5-diene-1-carboxyl-CoA (Ch1,5CoA)-forming Ch1CoA dehydrogenase was characterized after purification of the heterologously expressed gene. Both enzymes had a native molecular mass of 150 kDa and were composed of a single, 40- to 45-kDa subunit; both contained flavin adenine dinucleotide (FAD) as a cofactor. While the ChCoA dehydrogenase was competitively inhibited by Ch1CoA in the oxidative direction, Ch1CoA dehydrogenase further converted the product Ch1,5CoA to benzoyl-CoA. The results obtained suggest that Ch1,5CoA is a common intermediate in benzoate and crotonate fermentation that serves as an electron-accepting substrate for the two consecutively operating acyl-CoA dehydrogenases characterized in this work. In the case of benzoate fermentation, Ch1,5CoA is formed by a class II benzoyl-CoA reductase; in the case of crotonate fermentation, Ch1,5CoA is formed by reversing the reactions of the benzoyl-CoA degradation pathway that are also employed during the oxidative (degradative) branch of benzoate fermentation.
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cyclohexanecarboxyl coenzyme a coa and cyclohex 1 ene 1 carboxyl coa dehydrogenases two enzymes involved in the fermentation of benzoate and crotonate in syntrophus aciditrophicus
Journal of Bacteriology, 2013Co-Authors: Johannes W Kung, Jana Seifert, Martin Von Bergen, Matthias BollAbstract:The strictly anaerobic Syntrophus aciditrophicus is a fermenting deltaproteobacterium that is able to degrade benzoate or crotonate in the presence and in the absence of a hydrogen-consuming partner. During growth in pure culture, both substrates are dismutated to acetate and cyclohexane carboxylate. In this work, the unknown enzymes involved in the late steps of cyclohexane carboxylate formation were studied. Using enzyme assays monitoring the oxidative direction, a cyclohex-1-ene-1-carboxyl-CoA (Ch1CoA)-forming cyclohexanecarboxyl-CoA (ChCoA) dehydrogenase was purified and characterized from S. aciditrophicus and after heterologous expression of its gene in Escherichia coli. In addition, a cyclohexa-1,5-diene-1-carboxyl-CoA (Ch1,5CoA)-forming Ch1CoA dehydrogenase was characterized after purification of the heterologously expressed gene. Both enzymes had a native molecular mass of 150 kDa and were composed of a single, 40- to 45-kDa subunit; both contained flavin adenine dinucleotide (FAD) as a cofactor. While the ChCoA dehydrogenase was competitively inhibited by Ch1CoA in the oxidative direction, Ch1CoA dehydrogenase further converted the product Ch1,5CoA to benzoyl-CoA. The results obtained suggest that Ch1,5CoA is a common intermediate in benzoate and crotonate fermentation that serves as an electron-accepting substrate for the two consecutively operating acyl-CoA dehydrogenases characterized in this work. In the case of benzoate fermentation, Ch1,5CoA is formed by a class II benzoyl-CoA reductase; in the case of crotonate fermentation, Ch1,5CoA is formed by reversing the reactions of the benzoyl-CoA degradation pathway that are also employed during the oxidative (degradative) branch of benzoate fermentation.
