Laccase Encapsulation in ZIF-8 Metal-Organic Framework Shows Stability Enhancement and Substrate Selectivity.

Abstract

CgL1 laccase from Corynebacterium glutamicum was encapsulated into the metal‐organic framework (MOF) ZIF‐8 which was synthesized in a rapid enzyme friendly aqueous synthesis, the fastest in situ encapsulation of laccases reported to date. The obtained enzyme/MOF, i. e. laccase@ZIF‐8 composite showed enhanced thermal (up to 70 °C) and chemical (N,N‐dimethylformamide) stability, resulting in a stable heterogenous catalyst, suitable for high temperature reactions in organic solvents. Furthermore, the defined structure of ZIF‐8 produced a size selective substrate specificity, so that substrates larger than the pore size were not accepted. Thereby, 2’‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid) (ABTS) was used to verify that the enzyme is immobilized inside the MOF versus the outside surface. The enzyme@MOF composite was analyzed by atomic absorption spectroscopy (ASS) to precisely determine the enzyme loading to 2.1 wt%.