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.

Characterization and evaluation of immobilized enzymes for applications in flow reactors

“…Silica monoliths enable high loading (92 % yield, up to 80 mg x g carrier -1 ) and are suitable to work under high flow rate at low backpressure, obtaining high STYs ( up to 1229 g h -1 L -1 ) [45,46]. For instance, macrocellular silica monoliths prepared by a sol-gel method based on emulsion templating [47,48] have been used for the adsorption and covalent grafting of transaminases (16 % activity recovered). Besides silica, monoliths can be also formed with biopolymers [49] like agarose [50,51].…”

Flow Bioreactors as Complementary Tools for Biocatalytic Process Intensification

“…By tuning the reaction conditions, the same enzyme could be used for the mild oxidation of a large range of amines with excellent conversion yields [60]. Lentikats have also been shown to be valid alternatives for TAs in flow [61], as have silica monoliths, onto which the enzymes can be covalently attached [62].…”