Dissertation / PhD Thesis

FZJ-2016-04006

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Characterization of amino acid ammonia lyases & mutases for the production of chiral $\alpha$- and $\beta$-amino acids

Dreßen, A. (Corresponding author)FZJ*

2016
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-176-7

Please use a persistent id in citations: http://hdl.handle.net/2128/13017  urn:nbn:de:0001-2017032858

Abstract: Enantiopure non-natural amino acids are valuable building blocks for the production of chemicals and pharmaceuticals or are themselves pharmacologically active. Examples are 2-chloro-phenylalanine, a precursor for the production of a hypertension pharmaceutical and L-Dopa, which is used for the treatment of Parkinson desease or (R)-$\beta$-phenylalanine, which is part of the side chain of the antitumor drug Taxol. To get access to this class of compounds, a toolbox of MIO-dependent ammonia lyases and aminomutases was generated including four wild-type phenylalanine and tyrosine ammonia lyases (PAL/TAL), one variant with altered substrate specificity, and three wild-type phenylalanine and tyrosine aminomutases (PAM/TAM) from plants, yeast, and bacteria. All ammonia lyases were comparatively characterized with respect to kinetic parameters, pH- and T-optima for the deamination reaction of their natural substrates. Scince the focus of this thesis was on the stereoselective amination of cinnamic acid (CA) derivatives to yield enantiopure α- and β-amino acids, the investigation of the substrate ranges and reaction parameters was the main goal. Among the tested ammonia lyases in the toolbox PAL from $\textit{Arabidopsis thaliana}$ (AtPAL2), an enzyme which was not characterized in detail yet, performed best, compared to the enzymes from $\textit{Petroselinum cripsum}$ and $\textit{Rhodosporidium toruloides}$, which are well studied and industrially applied. AtPAL2 shows significant faster conversion of 3-F-CA (91.2 %), 4-F-CA (84.7 %) and 2-Cl-CA (96.4 %) in batch reactions. Due to the importance of 2-Cl-L-Phe as key intermediate for the production of hypertension drugs, this reaction was further investigated in larger scale using different reactor types and reaction modes. With a continuous enzyme membrane reactor the space-time-yield (STY) and productivity per catalyst (cell dry weight: CDW) could be enhanced from 11.8 g/L*d and 10.8 g/gDCW in batch to 67.8 g/L*d and 46.8 g/gDCW. The product 2-Cl-L-Phe could be isolated by simple volume reduction and crystallization with a yield of 57 % and high purity. [...]

Note: Heinrich-Heine-Universität Düsseldorf, Diss., 2016

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Contributing Institute(s):

1. Biotechnologie (IBG-1)

Research Program(s):

1. 581 - Biotechnology (POF3-581) (POF3-581)

Appears in the scientific report 2016

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Database coverage:
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