Taking innovative action on industrial organic synthesis Toxic materials are used in most industrial chemical processes, but researchers are looking to develop greener alternatives using biocatalysis. Researchers in the CarbaZymes project are drawing inspiration from the natural world to develop more sustainable processes, work which will have a positive impact on both society and industry, as Professor Wolf-Dieter Fessner explains
Engineering novel enzymes using advanced bioinformatics tools and screening for optimized catalyst properties.
The process of assembling simple fragments to build large, complex products by connecting carbon-carbon bonds (C–C bonds) is an essential technology at the heart of industrial organic synthesis. The current methods for creating C–C bonds are heavily reliant on metal catalysis, particularly involving rare noble metals, such as palladium or rhodium complexes. Ores for these materials can only be mined in a few locations across the world, an activity resulting in very significant pollution. “These mining sites are among the most polluted places on earth, causing global environmental damage via release of millions of tonnes of toxic waste into the air every year,” explains Professor Wolf-Dieter Fessner. “Many traditional chemical operations not only involve the use of such toxic materials, but also are very energy-intensive, as extremely high temperatures are generally required. It’s sometimes not only necessary to operate under such harsh conditions, but also to use activated reagents - the manufacture of these compounds themselves results in the accumulation of significant amounts of environmentally unfriendly waste materials.” As the Principal Investigators of the CarbaZymes project, Professor Fessner is exploring an alternative approach to forming C–C bonds by using enzymes from nature as efficient eco-friendly catalysts. The work of Professor Fessner and his colleagues in the project is largely motivated by concerns 22
around the sustainability of current methods. “A general greening of industrial processes would be very much in the interests of European citizens, and those beyond of course. There’s a strong trend in the chemical and pharmaceutical industries nowadays towards developing more sustainable biocatalytic processes,” he stresses. This is a topic that lies at the heart of the CarbaZymes project’s agenda. Whereas with traditional chemical methods product selectivity is difficult to achieve, biochemical catalysts for C–C bond formation synthesize the same products chemo-, regio- and stereo-selectively with exquisite precision, leading to the formation of chiral molecules containing up to two new adjacent chiral centres of known configuration. Enzymes can also achieve unparalleled rate acceleration under mild temperatures and pressures in a near neutral aqueous reaction media,
Sensitive high-throughput screening of enzyme arrays to rapidly identify novel enzyme activities..
thereby consuming much less energy while eliminating the use of hazardous solvents and reagents, with concomitant minimisation of waste and cost. “The ultimate ideal is to utilise renewable resources as starting materials. For example, taking compounds from nature, processing them with the aid of enzymes under sustainable conditions, and producing materials that can be recycled,” says Professor Fessner. A number of hurdles remain, however, before such a circular bioeconomy can become a reality. The research required is multi-disciplinary in nature, with Professor Fessner and his colleagues aiming to develop an unprecedented platform of novel C–C bond forming enzymes, in particular a specific class called lyases. “Specifically we’re looking at aldol reactions, which are actually well known to the organic chemist. Man’s efforts, however, pale into insignificance when compared to those of nature. Over millions of years, nature has evolved lyases for the efficient synthesis of a huge variety of different target compounds, many of which are totally unknown” he continues. “However, most such enzymes exhibit strict specificity for highly functionalised natural compounds, and are thus unlikely to be of immediate interest to industry, where low-functionalised substrates are the norm.” “It was actually with this challenge in mind that the CarbaZymes consortium
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was formed. The consortium now brings together capabilities enabling not only the discovery of suitable natural enzyme starting points, but their immediate engineering into demonstrated effective industrial biocatalysts for highly desirable aldol reactions tolerant to low-functionalised substrates.”
Enzyme catalysis The CarbaZymes project is responding to the heightened level of industrial demand by investigating the use of biocatalytic synthesis as a basis for the development of widely needed chemicals and active pharmaceutical ingredients. In this work researchers are drawing inspiration from the natural world, aiming to develop robust enzymes for C–C bond forming reactions. “We work with an SME that has a lot of expertise in utilising meta-genomic information. They have
for a polymer material, for chemicals that are utilised in bulk quantities across the world,” says Professor Fessner. “It’s clearly very important to establish more sustainable pathways to make such monomer materials as soon as we can. Even preventing a small fraction of pollution stemming from their production would still have a huge impact, as an enormous amount of these materials are produced chemically every year.” The wider, longer-term goal is to utilise sustainable resources as starting materials for next-generation synthetic biological processes, reducing our dependence on fossil fuels, which in the long run will help protect the environment and boost the competitiveness of European industry. While this is very much a long-term goal, Professor Fessner says that important progress has already been made in the course of the project. “Alongside
We aim to build on existing knowledge, to develop a platform with many robust enzymes and variants that could be applied for different purposes, under different conditions and for different new reactions useful in industry the capability to produce a large variety of enzymes via gene synthesis,” explains Professor Fessner. A second element of the project’s work centres around utilising and modifying known enzymes. “We aim to broaden their catalytic capabilities. This means broadening their substrate scope and broadening their window of tolerance for high concentrations of substrates, to achieve high concentrations of products that can be more easily isolated,” outlines Professor Fessner. “We are developing reactions that are likely not found anywhere in nature. These reactions are highly relevant as a more sustainable approach to major industrial processes.” Many of the enzymes commonly found in nature can in principle be applied in carboligation reactions, yet only a few have been investigated to a level where they can be utilised for industrial processes. Widening the knowledge base on these enzymes will bring them significantly closer to - or even into - practical application. “We aim to build on existing knowledge, to develop a platform with many robust enzymes and variants that could be applied for different purposes, under different conditions and for different new reactions useful in industry,” says Professor Fessner. This research is designed to respond effectively to market needs, and help boost the competitiveness of the European chemical and pharmaceutical industries. “For example, we are looking at monomers
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identifying suitable enzymes we’ve also been working to develop them to a stage where they can be directly applied in industrial settings,” he outlines. So far two patents have been filed, and now researchers are looking towards assessing the effectiveness of the reactions that have been developed. “We intend to scale-up those reactions that we have developed at lab scale, to the pilot level and maybe even larger scales. We will test the validity of our approach, and the suitability of these enzymes under applied conditions,” outlines Professor Fessner. “This work will be done in leading industrial labs. Ultimately, we hope CarbaZymes will represent a major stepping stone in paving the way towards a greener future!”
CARBAZYMES Sustainable industrial processes based on a C-C bond-forming enzyme platform Project Objectives
C-C bond forming reactions are at the heart of industrial organic synthesis, but remain largely unexplored due to the lack of broad biocatalytic reaction platforms. CARBAZYMES addresses this challenge by promoting innovation in the field of biocatalytic C-C bond formation at large scale, to strengthen the global competitiveness of the European chemical and pharmaceutical industry. Sustainable processes resulting from this research will have an environmental impact by replacing energy and resource intensive traditional processes.
Project Funding
Funded by the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No 635595
Project Partners
Coordinator
Contact Details
Professor Wolf-Dieter Fessner, Ph.D TU Darmstadt Dept of Organic Chemistry & Biochemistry Alarich-Weiss-Str. 4 D-64287 Darmstadt Germany T: +49 6151 16-23640 F: +49 6151 16-23645 E: fessner@tu-darmstadt.de W: http://carbazymes.com https://www.youtube.com/watch?v=iNlfyDa093g &list=PLvpwIjZTs-LjYqeOiYYqRWlegdihyjGgu
Wolf-Dieter Fessner, Ph.D
Wolf-Dieter Fessner obtained his Ph.D in 1986 and worked as a postdoctoral fellow with George Whitesides (Harvard University) and George Olah (USC, L.A.). Before assuming the chair in Organic Chemistry at the Technische Universität Darmstadt in 1998, he was professor at RWTH Aachen. His research interests are in the area of biocatalysis for applications in organic synthesis, with particular emphasis on the discovery and development of novel enzymes for stereoselective carbon-carbon bond forming reactions and the synthesis of complex oligosaccharides.
Analysis of structure-function principles of complex aldolase structures.
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