Self-Sufficient Flow-Biocatalysis by Coimmobilization of Pyridoxal 5′-Phosphate and ω-Transaminases onto Porous Carriers

• Ana I. Benítez-Mateos ^†
• Martina L. Contente ^§
• Susana Velasco-Lozano ^⊥
• Francesca Paradisi ^*§
• Fernando López-Gallego ^*⊥‡

• ^† Heterogeneous Biocatalysis Laboratory, CICbiomaGUNE, Paseo Miramón 182, Edificio empresarial C”, 20014 San Sebastián, Spain
• ^§ School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K
• ^⊥ Heterogeneous biocatalysis laboratory, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH−CSIC), University of Zaragoza, C/Pedro Cerbuna 12, 50009 Zaragoza, Spain
• ^‡ ARAID, Aragon I+D foundation, Zaragoza, Spain

We expanded the application of self-sufficient heterogeneous biocatalysts containing coimmobilized ω-transaminases and pyridoxal 5′-phosphate (PLP) to efficiently operate packed-bed reactors in continuous flow. Using a ω-transaminase from Halomonas elongata coimmobilized with PLP onto porous methacrylate-based carriers coated with polyethylenimine, we operated a packed-bed reactor continuously for up to 50 column volumes at 1.45 mL × min–1 in the enantioselective deamination of model amines (α-methylbenzyl amine), yielding >90% conversion in all cycles without exogenous addition of cofactor. In this work, we expanded the concept of self-sufficient heterogeneous biocatalysts to other ω-transaminases such as the ones from Chromobacterium violaceum and Pseudomonas fluorescens. We found that enzymes with lower affinities toward PLP present lower operational stabilities in flow, even when coimmobilizing PLP. Furthermore, ω-transaminases coimmobilized with PLP were successfully implemented for the continuous synthesis of amines and the sustainable metrics were assessed. These results give some clues to exploit PLP-dependent ω-transaminases under industrially relevant continuous operations in a more cost-effective and environmentally friendly process.

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