Biphasic reaction systems for enzyme catalysis are an elegant way to overcome limited solubility and stability of reactants and facilitate continuous processes. However, many synthetically useful enzymes are not stable in biphasic systems of water and organic solvent. The entrapment in polymer beads of polyvinyl alcohol has been shown to enable the stable operation of enzymes unstable in conventional biphasic reaction systems. We report the extension of this concept to continuous operation in a fluidised bed reactor. The enzyme benzaldehyde lyase was used for the continuous synthesis of enantiopure (R)-3,3'-furoin. The results show enhanced stability with half-life times under operation conditions of more than 100 h, as well as superior enzyme utilisation in terms of productivity. Furthermore, racemisation and oxidation of the product could be successfully prevented under the non-aqueous and inert reaction conditions.
Separation into stable aqueous compartments is a promising concept to enable the synthetic application of biocatalysts in unfavourable non-aqueous media, and might provide the key for successful application of complex multistep synthesis. This study describes and evaluates the practical utility of polyvinyl alcohol (PVA) cryogels as a matrix for such compartmentation. The protocol for enzyme entrapment in the gels was highly efficient, giving an immobilization yield of !/99% and a total loss of material less than 10%. The resulting gel compartments were between 2.2 and 4 mm in size and had high mechanical strength. Shrinking occurred in solvents with the ability for water uptake. The matrix enabled the synthetic use of benzaldehyde lyase and alcohol dehydrogenase in hexane, in which equilibrium concentrations were comparable to a conventional two-phase system. The results suggest a general suitability of PVA gels for the compartmentation of biocatalyzed reactions in non-aqueous media.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.