Biochemical Characterization of Phenylacetaldehyde Dehydrogenases from Styrene-degrading Soil Bacteria
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Biochemical Characterization of Phenylacetaldehyde Dehydrogenases from Styrene-degrading Soil Bacteria Juliane Zimmerling 1 & Michel Oelschlägel 1 & Carolin Großmann 1 & Matthias Voitel 1 & Michael Schlömann 1 & Dirk Tischler 1,2 Received: 4 April 2020 / Accepted: 11 September 2020/ # The Author(s) 2020
ABSTRACT
Four phenylacetaldehyde dehydrogenases (designated as FeaB or StyD) originating from styrene-degrading soil bacteria were biochemically investigated. In this study, we focused on the Michaelis-Menten kinetics towards the presumed native substrate phenylacetaldehyde and the obviously preferred co-substrate NAD+. Furthermore, the substrate specificity on four substituted phenylacetaldehydes and the co-substrate preference were studied. Moreover, these enzymes were characterized with respect to their temperature as well as long-term stability. Since aldehyde dehydrogenases are known to show often dehydrogenase as well as esterase activity, we tested this capacity, too. Almost all results showed clearly different characteristics between the FeaB and StyD enzymes. Furthermore, FeaB from Sphingopyxis fribergensis Kp5.2 turned out to be the most active enzyme with an apparent specific activity of 17.8 ± 2.1 U mg-1. Compared with that, both StyDs showed only activities less than 0.2 U mg-1 except the overwhelming esterase activity of StyD-CWB2 (1.4 ± 0.1 U mg-1). The clustering of both FeaB and StyD enzymes with respect to their characteristics could also be mirrored in the phylogenetic analysis of twelve dehydrogenases originating from different soil bacteria. Keywords Oxidoreductase . NAD+ . Maximum reaction rate . Michaelis constant . Turnover number . Evolutionary ancestry . Esterase activity
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12010-02003421-8) contains supplementary material, which is available to authorized users.
* Juliane Zimmerling [email protected]–freiberg.de * Dirk Tischler [email protected]
1
Interdisciplinary Ecological Center, Environmental Microbiology Group, TU Bergakademie Freiberg, Leipziger Str. 29, 09599 Freiberg, Germany
2
Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany
Applied Biochemistry and Biotechnology
INTRODUCTION Aldehyde dehydrogenases (ALDHs, EC 1.2.1) comprise a huge group of enzymes occurring in every organism ranging from bacteria and fungi to invertebrates and mammals [1]. Enzymes belonging to this class transform a wide range of substrates during different metabolic routes, and they are strictly co-substrate-dependent. The substrate spectra of these enzymes comprise aldehydes which are oxidized to acids while reducing NAD(P)+. By means of the 145 aligned ALDHs, ten conserved motifs could be detected [1]. Four of them were allocated to the co-substrate binding region and three to the catalytic site. On the basis of the three catalytic amino acids cysteine, glutamate and asparagine, the catalytic mechanism of ALDHs c
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