Reusable ω-transaminase sol-gel catalyst for the preparation of amine enantiomers

Abstract

<p>Heterogeneous &omega;-transaminase sol-gel catalysts were prepared and characterized in terms of immobilization degree, loading capacity and catalytic behavior in the kinetic resolution of racemic 1-phenylethylamine (a model compound)<em> </em>with sodium pyruvate in phosphate buffer (pH 7.5). The catalyst obtained when &omega;-transaminase from <em>Arthrobacter sp</em>. was encapsulated from the aqueous solution of the enzyme, isopropyl alcohol and polyvinyl alcohol in the sol-gel matrices, consisting of the 1:5 mixture of tetramethoxysilane and methyltrialkoxysilane, proved to be optimal including the reuse and storage stabilities of the catalyst. &nbsp;The optimized immobilizate was shown to perform well in the kinetic resolution of four structurally different aromatic primary amines in aqueous DMSO (10 v/v-%). The enzyme preparation showed synthetic potential by enabling the catalyst reuse in five consecutive preparative scale kinetic resolutions using 100 mM 1-phenylethylamine in aqueous DMSO (10 v/v-%). It was typical to fresh catalyst preparations that the kinetic resolution tended to exceed 50% before the reaction stopped leaving the (<em>S</em>)-amine unreacted while thereafter in reuse the reactions stopped at 50% conversion as expectable to highly enantioselective reactions.</p>