KIT Presseinformationen 016/2022

Press release 016/2022

Biotechnology: Enzymes in a Cage

Metal Organic Frameworks (MOFs) Increase Stability of Biocatalysts and Enable Their Use in Organic Solvents - KIT Researchers Demonstrate Enzyme MOF Flow Reactor

Photo: Dr. Raphael Greifenstein, KIT

3D model of a MOF in front of the enzyme MOF flow reactor in the laboratory at the KIT Institute for Functional Interfaces. (Photo: Dr. Raphael Greifenstein, KIT)

Enzymes accelerate many chemical reactions as biocatalysts. Researchers at the Karlsruhe Institute of Technology (KIT) have now incorporated enzymes into metal-organic cages (MOFs). They then demonstrated for the first time that the stabilization provided by these framework structures is even sufficient for use of the enzymes in a continuously operated reactor. Also new: The enzymes embedded in MOFs can be used not only in aqueous solvents, but also in organic solvents. The researchers report in the journal Angewandte Chemie (DOI: 10.1002/anie.202117144).

They are considered true multifunctional talents: enzymes accelerate many chemical reactions as catalysts. In organisms, they are involved in vital processes. In technology and industry, they are tools of white biotechnology that help save energy and conserve resources. Enzymes in detergents, for example, dissolve dirt at low temperatures. Enzymes are also used in environmental technology, food processing, drug production, medical diagnostics and many other areas.

Enzymes are mostly proteins. In order to exploit the potential of these giant molecules outside biological contexts in so-called cell-free biotechnology, they must be stabilized and integrated into efficient reactor systems. This challenge, which is central to white biotechnology, has already been overcome in many cases in aqueous solvents. In organic solvents, however, destabilization or denaturation often occurs - the catalytic properties are lost.

Researchers at the Institute of Functional Interfaces (IFG), the Institute of Nanotechnology, and the Institute of Biological Interfaces 1 - Biomolecular Micro- and Nanostructures of KIT have now succeeded in stabilizing enzymes in such a way that they can be used in both aqueous and organic solvents. Thus, they were able to demonstrate for the first time a continuous enzyme reactor system with high productivity and stability. The scientists report on this in the journal Angewandte Chemie.

MOFs simplify separation of catalysts and products

The innovative reactor system is based on metal-organic frameworks (MOFs). These are frameworks of metallic nodes and organic connecting struts that are characterized by crystalline structures and defined pore sizes. Through different combinations of metal building blocks and organic ligands as well as variations in pore size, MOFs can be tailored for very different applications. When used cell-free with enzymes, they act like cages. "We get the enzymes to diffuse individually into the pores of the MOFs, that is, to slip into the cage voluntarily, so to speak," explains Professor Christof Wöll, head of the IFG. "The MOFs act as armor, protecting these sensitive biomolecules and preventing denaturation." Thanks to the porosity of MOFs, the transport of reactants, the substances consumed during chemical reactions, and products formed in the process can be better controlled. In addition, MOFs simplify the laborious separation of catalyst and products, as explained by Professor Matthias Franzreb, deputy director of the IFG and co-author of the study.

Graphic: Dr. Raphael Greifenstein, KIT

The giant biomolecules diffuse individually into the precisely designed pores of a metal-organic scaffold. (Graphic: Dr. Raphael Greifenstein, KIT)

The Karlsruhe researchers demonstrated the time- and cost-efficient fabrication of an enzyme-MOF flow reactor. In this process, the stability of the immobilized enzyme was about 30 times higher than that of the free enzyme. The catalytic activity was about 30 percent compared to the free enzyme - quite a high value considering the deformation of the enzyme embedded in the MOF pores. The study ran in the context of the Cluster of Excellence "3D Matter Made to Order" of KIT and Heidelberg University and the Helmholtz program "Materials Systems Engineering". In further work on the topic, it is planned to use computer-based methods to modify the MOFs in such a way that deformation through the pores does not lead to a reduction but to an increase in activity.

Original publication (open access):

Raphael Greifenstein, Tim Ballweg, Tawheed Hashem, Eric Gottwald, David Achauer, Frank Kirschhöfer, Michael Nusser, Gerald Brenner-Weiß, Elaheh Sedghamiz, Wolfgang Wenzel, Esther Mittmann, Kersten S. Rabe, Christof M. Niemeyer, Matthias Franzreb, Christof Wöll: MOF-hosted enzymes for continuous flow catalysis in aqueous and organic solvents. Applied Chemistry, International Edition. 2022. doi: 10.1002/anie.202117144

https://onlinelibrary.wiley.com/doi/10.1002/anie.202117144

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or, 02.03.2022