The studied aldehyde oxidoreductase enzyme (AOR) incorporates in its active centre a tungsten ion, the heaviest element with biological function. Tungsten-containing enzymes occur only in bacteria and archaea, are very oxygen-sensitive and catalyze reactions with very low redox potential.

The studied AOR was isolated from Aromatoleum aromaticum (AORAa) a mesophilic and facultative anaerobic bacterium. AORAa characteristics differ significantly from the best-studied examples of AOR from the hyperthermophilic archaea. It is less oxygen-sensitive and has a more complicated structure. The AORAa catalyses the oxidation of a wide variety of aldehydes to the respective acids with either viologen dyes or NAD+ as electron acceptors.[1]

 

 

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Fig 1. AOR catalyzes O2-independent oxidation of aldehydes to corresponding carboxylic acids or the reverse reaction in a two-electron redox reaction.

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Our research aims to characterize the structure of the protein and its catalytic properties as well as solve
the mechanism of the catalyzed reaction. To achieve that we combine the experimental methods (i.e. kinetic measurements) with theoretical approaches.

 

 

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Fig.2. Hypothetical model of AOR from Aromatoleum aromaticum complex: yellow-catalytic subunit containing the tungsten cofactor (WCo) as a catalytic centre and one Fe4S4 cluster, orange-the electron transfer subunit containing four Fe4S4 clusters,  red-subunit containing a FAD cofactor.

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The project is conducted under the NCN grant PRELUDIUM No 2017/27/N/ST4/02676: ‘Tungsten-containing aldehyde oxidoreductase from Aromatoleum aromaticum - a study of catalytic reaction mechanism’ and Interdisciplinary Environmental Doctoral Studies "Physical, Chemical and Biophysical Foundations of Modern Technologies and Materials Engineering" (FCB). The project is conducted in close cooperation with the Faculty of Materials Science and Ceramics AGH University of Science and Technology and Philipps-Universität Marburg.

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Publications on the topic:

1. F.  Arndt , G. Schmitt, A.  Winiarska, M. Saft, A. Seubert, J. Kahnt,  J. Heider,   Characterization of an Aldehyde Oxidoreductase From the Mesophilic Bacterium Aromatoleum aromaticum EbN1, a Member of a New Subfamily of Tungsten-Containing Enzymes. Front. Microbiol., 10 (2019) 71. doi: 10.3389/fmicb.2019.00071

2. A. Winiarska, J. Heider, M. Szaleniec. D. Hege, F. Arndt „Sposób otrzymywania aldehydów poprzez enzymatyczną redukcję kwasów karboksylowych”, Polish Patent Application P.437445 (29.03.2021)

3. A. Winiarska, J. Heider, M. Szaleniec. D. Hege, F. Arndt „Sposób enzymatycznej redukcji formy utlenionej dinukleotydu nikotynowo-adeninowego.” Polish Patent Application P.437449 (29.03.2021)

4. A. Winiarska, J. Heider, M. Szaleniec. D. Hege, F. Arndt, A. Wojtkiewicz „A method of enzymatic reduction of the oxidized nicotinamide adenine dinucleotide and carboxylic acids”, European Patent Application EP22164459.4

5. A. Winiarska, D. Hege, Y. Gemmecker, J. Kryściak-Czerwenka, A. Seubert, J. Heider, M. Szaleniec, Tungsten Enzyme Using Hydrogen as an Electron Donor to Reduce Carboxylic Acids and NAD+, ACS Catalysis, 2022, 12 (14), 8707-8717, doi: 10.1021/acscatal.2c02147

6. P. Kalimuthu, D. Hege, A. Winiarska, Y. Gemmecker, M. Szaleniec, J. Heider, P. V. Bernhardt, Electrocatalytic Aldehyde Oxidation by a Tungsten Dependent Aldehyde Oxidoreductase from Aromatoleum Aromaticum, Chem. Eur. J. doi: 10.1002/chem.202203072