title: Immobilization of Phenylalanine Ammonia-Lyase on Single-Walled Carbon Nanotubes for Stereoselective Biotransformations in Batch and Continuous-Flow Modes.
abstract: Carboxylated single-walled carbon nanotubes (SwCNTCOOH) were used as a support for the covalent immobilization of phenylalanine ammonia-lyase (PAL) from parsley by two different methods. The nanostructured biocatalysts (SwCNTCOOH-PALIand SwCNTCOOH-PALII) with low diffusional limitation were tested in the batch-mode kinetic resolution of racemic 2-amino-3-(thiophen-2-yl)propanoic acid (1) to yield a mixture of (R)-1and (E)-3-(thiophen-2-yl)acrylic acid (2) and in ammonia addition to2to yield enantiopure (S)-1. SwCNTCOOH-PALIIwas a stable biocatalyst (>90 % of the original activity remained after six cycles with1and after three cycles in 6 m NH3with2). The study of ammonia addition to2in a continuous-flow microreactor filled with SwCNTCOOH-PALII(2 m NH3, pH 10.0, 15 bar) between 30-80 °C indicated no significant loss of activity over 72 h up to 60 °C. SwCNTCOOH-PALIIin the continuous-flow system at 30 °C was more productive (specific reaction rate,rflow=2.39 μmol min-1g-1) than in the batch reaction (rbatch=1.34 μmol min-1g-1).
authors.affiliation: Biocatalysis and Biotransformation Research Group, Babeş-Bolyai University of Cluj-Napoca, Arany János str. 11, 400028 Cluj-Napoca (Romania).
authors.forename: Judith H
authors.initials: JH
authors.lastname: Bartha-Vári
authors.affiliation: Biocatalysis and Biotransformation Research Group, Babeş-Bolyai University of Cluj-Napoca, Arany János str. 11, 400028 Cluj-Napoca (Romania).
authors.forename: Monica I
authors.initials: MI
authors.lastname: Toşa
authors.affiliation: Biocatalysis and Biotransformation Research Group, Babeş-Bolyai University of Cluj-Napoca, Arany János str. 11, 400028 Cluj-Napoca (Romania).
authors.forename: Florin-Dan
authors.initials: FD
authors.lastname: Irimie
authors.affiliation: Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Műegyetem rkp. 3, 1111 Budapest (Hungary).
authors.forename: Diána
authors.initials: D
authors.lastname: Weiser
authors.affiliation: Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Műegyetem rkp. 3, 1111 Budapest (Hungary); SynBiocat Ltd, Lázár deák u 4/1, 1173 Budapest (Hungary).
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Boros
authors.affiliation: Department of Biotechnology and Food Sciences, Budapest University of Technology and Economics, Szt. Gellért tér 4, 1111 Budapest (Hungary); Institute of Enzymology, Research Centre for Natural Sciences of Hungarian Academy of Sciences, Magyar tudósok krt. 2, 1117 Budapest (Hungary).
authors.forename: Beáta G
authors.initials: BG
authors.lastname: Vértessy
authors.affiliation: Biocatalysis and Biotransformation Research Group, Babeş-Bolyai University of Cluj-Napoca, Arany János str. 11, 400028 Cluj-Napoca (Romania).
authors.forename: Csaba
authors.initials: C
authors.lastname: Paizs
authors.affiliation: Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Műegyetem rkp. 3, 1111 Budapest (Hungary); SynBiocat Ltd, Lázár deák u 4/1, 1173 Budapest (Hungary).
authors.forename: László
authors.initials: L
authors.lastname: Poppe
keywords: biotransformations; enzyme catalysis; immobilization; nanotubes; supported catalysts