Enantioselective Transamination in Continuous Flow Mode with Transaminase Immobilized in a Macrocellular Silica Monolith

Abstract

ω-Transaminases have been immobilized on macrocellular silica monoliths and used as heterogeneous biocatalysts in a continuous flow mode enantioselective transamination reaction. The support was prepared by a sol-gel method based on emulsion templating. The enzyme was immobilized on the structured silica monoliths both by adsorption, and by covalent grafting using amino-functionalized silica monoliths and glutaraldehyde as a coupling agent. A simple reactor set-up based on the use of a heat-shrinkable Teflon tube is presented and successfully used for the continuous flow kinetic resolution of a chiral amine, 4-bromo-α-methylbenzylamine. The porous structure of the supports ensures effective mass transfer and the reactor works in the plug flow regime without preferential flow paths. When immobilized in the monolith and used in the flow reactor, transaminases retain their activity and their enantioselectivity. The solid biocatalyst is also shown to be stable both on stream and during storage. These essential features pave the way to the successful development of an environmentally friendly process for chiral amines production.

Macrocellular Titanosilicate Monoliths as Highly Efficient Structured Olefin Epoxidation Catalysts

“…The shape and the high void fraction of these macrocellular foams make them particularly suitable to be used in continuous flow reactors . Also, the specific surface area – which is generally high due to the presence of micro‐ and mesopores in the macropore walls – can be easily functionalized, allowing the monolith to be used as support for catalyst particles and enzymes …”

“…The nominal loading was investigated in the 1.8–10 % range. Si(HIPE) monolith, without titanium, was also prepared for comparison …”

Use of Immobilized Amine Transaminase from Vibrio fluvialis under Flow Conditions for the Synthesis of (S)‐1‐(5‐Fluoropyrimidin‐2‐yl)‐ethanamine

“…Powdery materials can be used as carriers and packed in a fixed bed reactor as well as porous monoliths, which have been successfully used for ATA immobilization. [30][31] Flow chemistry, along with enzyme immobilization, can circumvent some critical issues of biocatalytic reactions, thus positively influencing the outcome of the biotransformation. [32] In particular, whereas enzyme immobilization can improve enzyme stability, operating under flow-conditions can significantly reduce substrate/product inhibition effects and push forward unfavorable reaction equilibria through the continuous removal of the product from the reaction site.…”

Continuous flow (micro-)reactors for heterogeneously catalyzed reactions: Main design and modelling issues

“…The choice of silica is appropriate being a non toxic compound, inert, quite inexpensive and highly surface functionalised, so to allow enzyme anchoring. The monoliths were used for the production of chiral amines as precursors for drugs [59].…”