| dc.description.abstract | Recently, our group has successfully embedded catalase (CAT) into zeolitic imidazolate frameworks-90 (ZIF-90) via de novo approach. In the de novo approach, the ZIF-90 are grown around the enzyme molecules under a mild synthetic condition. Remarkably, the biological activity of biocomposites is able to be maintained as proteinase K, the enzyme that can digest proteins, is existing with large molecule size due to the size selectivity of ZIF-90 porous.
In this work, we hypothesized that the enzyme molecules are confined in the tight mesoporous cavities left in the MOF crystals by growth of the framework around the enzyme molecules which reduces the structural changes of enzymes. In order to test this hypothesis, we exposed the CAT@ZIF-90 to and free CAT to a denature reagent (i.e., urea) and high temperatures (i.e., 80 °C) and examined their resulting catalytic activity, accompanied by fluorescence spectroscopy to monitor the structural conformation changes of the enzymes. The results show that embedded CAT maintains its biological function even when exposed to 6 M urea and 80 °C, respectively, while free CAT shows undetectable activity. A fluorescence spectroscopy study indicates that the structural conformation of the embedded CAT changes less under these denaturing conditions than free CAT. We have not only demonstrated that CAT maintains its biological function under unfolding conditions after being embedded in ZIF microcrystals via a de novo approach but also performed fluorescence spectroscopy to provide an in situ observation that the structural conformation of CAT in ZIFs is mostly maintained. | en_US |