Peter-Leon Hagedoorn’s group

Peter-Leon Hagedoorn’s group at Delft University of Technology, focuses on the elucidation of reaction mechanisms of (metallo-)enzymes containing heme, Fe-S clusters and/or W/Mo cofactors. We use microsecond timescale rapid mixing techniques, unique in the world, employed in a continuous flow UV-vis spectrophotometric device called Nanospec, and a rapid freeze hyperquench device called MHQ.

These techniques are circa 100 times faster than commercial instruments, and both techniques have been very powerful in the discovery of novel transient intermediates in the heme enzyme chlorite dismutase and Cu2+ binding to ATCUN/NTS motif peptides. In recent years Hagedoorn ventured together with prof. Hanefeld into enzyme immobilization and flow biocatalysis using Mn2+ dependent aldolases and hydroxynitrile lyases as well as thermophilic glycosyl transferases and hydratases (including FeS cluster containing enzymes).

Within the W-BioCat project, our focus is on the recombinant expression and characterization of W-containing aldehyde oxidoreductases (AORs). Heterologous expression of W-enzymes is challenging due to the requirement of an efficient W-cofactor biosynthesis pathway. The W-BioCat strains developed in this project will enable expression of new W-enzymes from genetic databases, and facilitate production of new engineered W-enzymes.

OxyCat group

The research of the OxyCat group, led by Frank Hollmann at Delft University of Technology, focuses on the establishment of new #redox chemistry using #biocatalysts.

One focus of the group lies on #oxyfunctionalisation reactions, i.e. oxidations where an oxygen atom is introduced into C-H-, C-C-, C=C-bonds. Performing these transformations selectively with traditional chemistry is notoriously difficult. A particular focus in the OxyCat group lies on Peroxygenases as #catalysts. These H2O2-dependent heme oxygenases excel by their robustness against hostile reaction conditions and their catalytic performance. Our objective is to develop reaction conditions allowing for their economical use. This entails, medium engineering to achieve product concentrations above 100 gL-1, reaction engineering to maximise the catalytic performance of the #biocatalyst and establish scalable 𝘪𝘯 𝘴𝘪𝘵𝘶 H2O2 generation systems.

Within the W-BioCat project, our focus will lie on the exploration of W-containing aldehyde oxidoreductases (AORs) for the #catalytic reduction of #carboxylic acids. In earlier studies, we have demonstrated the principal feasibility H2- or syngas-driven acid reductions using 𝑃𝑦𝑟𝑜𝑐𝑜𝑐𝑐𝑢𝑠 𝑓𝑢𝑟𝑖𝑜𝑠𝑢𝑠. The high selectivity of this reduction reaction and the controllable degree of reduction offers exciting possibilities for the valorisation of (waste) fatty acids as building blocks for chemical synthesis and as performance additives.

Vincent's group

The Vincent group is based in the #Chemistry Department at the University of Oxford, UK. We are a primarily a bio-inorganic research group, with an interest in small molecular activation at metal centres in #enzymes. We have worked on #hydrogenase enzymes for several decades. These enzymes are inspirational to chemists because they use a catalytic site built from earth-abundant metals - nickel and/or iron - to activate hydrogen gas. In contrast, chemists still rely heavily on precious metals such as platinum or palladium for activating hydrogen. The Vincent group have developed a range of tools for studying the mechanism of the highly active #hydrogenase enzymes by coupling #electrochemistry with spectroscopy. We make extensive use of infrared spectroscopy, which reports on the vibrational changes at CO and CN- ligands at the active site of hydrogenases, while using electrochemistry to switch on/off #catalysis during measurements.

More recently, we have demonstrated #electrochemical control over single crystals of hydrogenase, allowing us to collect X-ray diffraction structures in well-defined redox states relevant to the catalytic cycle. This makes important links between observations made on solution samples and crystals of these enzymes. We have built up a significant structural biology sub-group, and are extending these approaches to other #metalloenzymes with roles in small #molecule activation, such as nitrogenase.

Our work on hydrogenases led us into biotechnology about 12 years ago. In particular, we became interested in more #sustainable ways of driving biocatalysis, replacing carbon-based reductants with hydrogen gas. We have developed #hydrogen-driven systems for recycling the reduced cofactors NADH and NADPH and flavins for application in biotechnology, and more recently we have developed a biocatalytic system for hydrogen-driven reduction of nitro-group to amines. We are also developing methods for reductant supply to dioxygen-dependent enzymes using safe mixtures of dihydrogen/dilute dioxygen. A key motivation for us is to make #bicoatalysis easier to operate, more atom-efficient, and more sustainable.

Our catalyst developments for #biotechnology are informed by our use of electrochemistry: we study enzyme #redox reactions as separate half reactions at an electrode, for example, the oxidation of dihydrogen, or the reduction of NAD+, allowing us to combine components in unique ways on electrically-conductive supports. We take inspiration from the model of ‘mixed potential theory’ discussed in heterogeneous catalysis. Our favourite support material is #carbon black, since it is already well-established as an industrial catalyst support and allows facile immobilisation of enzymes by direct adsorption. Since the enzymes are immobilised on carbon particles, these heterogeneous biocatalyst systems are ideal for translation into continuous flow, and we have applied #biocatalytic hydrogenations in continuous flow.