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2995854 
Journal Article 
Phenylalanine ammonia-lyase catalyzed deamination of an acyclic amino acid - Enzyme mechanistic studies aided by a novel microreactor filled with magnetic nanoparticles 
Weiser, D; Bencze, L; Bánóczi, G; Ender, F; Kiss, R; Kókai, E; Szilágyi, A; Vértessy, BG; Farkas, Ö; Paizs, C; Poppe, L 
2015 
Yes 
ChemBiochem
ISSN: 1439-4227
EISSN: 1439-7633 
English 
26345352 
Phenylalanine ammonia-lyase (PAL), in many organisms, catalyzes the deamination of L-phenylalanine (Phe) to (E)-cinnamate by the aid of its MIO prosthetic group. By using PAL, immobilized on magnetic nanoparticles and fixed in a microfluidic reactor with an in-line UV detector, we first demonstrated that PAL can catalyze the ammonia elimination from the acyclic propargylglycine (PG) to yield (E)-pent-2-ene-4-ynoate indicating new opportunities to extend the MIO-enzyme toolbox towards acyclic substrates. Deamination of PG, being acyclic, cannot involve a Friedel-Crafts-type attack at an aromatic ring. The reversibility of the PAL-reaction, also demonstrated by the ammonia addition to (E)-pent-2-ene-4-ynoate yielding enantiopure L-PG, contradicts the proposed highly exothermic single-step mechanism. Computations on the QM/MM models of the N-MIO intermediates from L-PG and L-Phe in PAL, showing similar arrangements within the active site, support a mechanism via the N-MIO intermediate.