Biotransformation by enzymes of the nitrile metabolism

( L. Martínková, M. Chmátal, V. Křen, M. Pátek, L.Rucká, J. Nešvera)

Nitrile hydrolysis is an important step in the synthesis of carboxylic acids and amides (building
blocks for the synthesis of fine and pharmaceutical chemicals). It has been traditionally carried
out under extreme conditions (strong acids or bases, high temperatures). The disadvantages of this
method are high energy costs, low yields and missing selectivities.

However, the enzymes of the nitrile metabolism (Figure 1) perform these reactions under mild
conditions, enantio- or regioselectively and with high yields. These enzymes consist of nitrilases
and nitrile hydratases which transform nitriles into carboxylic acids and amides, respectively.
Amides are then hydrolyzed by amidases. The synthesis of nitriles from aldoximes is catalyzed by
aldoxime dehydratases. *

Figure 1: Reactions catalyzed by enzymes of nitrile metabolism

The focus of our work is on the acquisition of new representatives of the aforementioned enzymes,
e.g. by mining gene databases (GenBank) and expressing the selected, artificially synthesized genes
in . In this way a set of more than 15 nitrilases from filamentous fungi was constructed. These
catalysts (cells, purified enzymes) were used in the synthesis of alfa-hydroxy acids (building
blocks, cosmetics) or new derivatives of taxol (anticancer drug) from the corresponding
nitriles.

Some bacterial nitrilases were prepared analogously and proved useful in the biotransformation of
benzonitrile herbicide residues into less toxic and biodegradable carboxylic acids (Figure 2).

Figure 2: Enzymatic detoxication of benzonitrile herbicides

Literature

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  herbicides via the nitrile hydratase-amidase pathway in rhodococci. J Ind Microbiol Biotechnol
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• Veselá AB, Křenková A, Martínková L (2015) Exploring the potential of fungal
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• Wilding B, Veselá AB, Perry JJB, Black GW, Zhang M, Martínková L, Klempier N (2015) An
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• Veselá AB, Rucká L, Kaplan O, Pelantová H, Nešvera J, Pátek M, Martínková L. (2016)
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• Martínková L, Rucká L, Nešvera J, Pátek M (2017) Recent advances and challenges in the
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Cooperation

• P. Lovecká et al., University of Chemical Technology, Prague
• N. Klempier, TU Graz, Austria
• M. Cantarella, University of L´Aquila, Italy
• T.C. Bhalla, University of Himachal-Pradesh, India
• CMST-Action CM1303, Systems Biocatalysis – SysBiocat