The Electrochemical Leaf:Rapid, Reversible Cycling of Nicotinamide Cofactors for Enzyme-based Organic Synthesis

Lead Research Organisation: University of Oxford
Department Name: Mathematical, Physical&Life Sciences Div

Abstract

A new invention, the 'Electrochemical Leaf' integrates a universal component of green leaves with a conducting metal oxide to produce a unique bio-hydrid material to drive enzyme-based organic synthesis. The 'Leaf is a platform technology with numerous applications. The first bond-forming stage of photosynthetic CO2 uptake in plants involves a simple enzyme called ferredoxin-NADP-reductase (FNR) which uses photo-excited electrons to recycle the 'nicotinamide' cofactor NADPH that is consumed (yielding NADP+) in the primary CO2-fixing process (Calvin cycle). In the 'Leaf, FNR is embedded in mesoporous indium tin oxide (ITO) deposited on a support, resulting in an electrode (FNR@ITO/support) that recycles NADPH/NADP+ rapidly and reversibly, using electricity. More than 1000 enzymes use nicotinamides in selective organic reactions, but industry cannot exploit this chemistry. The 'Leaf' is a platform technology that represents a step change.

Publications

10 25 50
 
Description We have investigated a number of biosynthetic reactions and started a very productive collaboration with Nick Turner (University of Manchester) aimed at revolutionising the study and exploitation of organic synthesis catalysed by redox enzymes. A very important new factor is our ability to monitor, continuously, the progress of the reaction underway, and make interventions to check different aspects and make adjustments. We are examining reductive amination, imine reduction, alcohol/ketone interconversions and carboxylate reduction using the respective 'coupling enzymes'. We have designed reactors in which the process is turned into a fuel cell. In one case, we have used hydrogen to convert 2-ketoglutarate and ammonia into L-glutamate, and used this reaction to study the kinetics of the two-enzyme system (now published 2018). In another case, we use air (passed over a Pt cathode) to convert alcohols into ketones, in many examples with R/S stereoselectivity.
In what is a major discovery, we have established that the electrochemical leaf works because of nanoconfinement of two different enzymes between which NADP(H) can be recycled very rapidly. The coupling enzyme (E2) must bind very close to the NADP(H) recycling enzyme FNR, within each of the billions of nanospaces formed by electrophoretic deposition of indium tin oxide (ITO) nanoparticles. The nanoconfinement of FNR, E2 and NADP(H) in the nanozones |(analogous to that represented by a 10 x 10 x 10 nm cube) results in a massive increase in the concentration of each component and minimises the distance that NADP(H) must transfer during recycling. The system is unique in linking cofactor recycling between two enzymes trapped in electrode nanopores, fast and reversible electrochemical driving of NADP(H) via one of the enzymes (FNR), and sophisticated organic transformations by E2, which can be any of hundreds of different oxidoreductase. A patent is now published. We have shown that we now have a method for setting up and controlling extended enzyme cascades, effectively making myriad enzymes directly controllable and observable by electrochemical technology. We are now developing the technology along further fronts: we have starting using titanium foam as the support, which offers a very high surface area. As well as revolutionalising biocatalyst discovery (because real-time observation and control makes this so easy) we are now designing scaled-up reactors that should be proof-of-principle for pharma companies and we have designed a system for deracemizing secondary alcohols. Most recently we are exploiting the technology platform to investigate inhibitors of cancer-associated enzymes.
Exploitation Route The concept of an energising, controlling and monitoring enzyme cascades trapped in electrode nanopore zones is unprecedented. New fundamental studies will include materials, mathematics, enzymology and organic synthesis via biocatalysis. The work is poised to revolutionise enzyme-based organic synthesis because not only are we able to recycle nicotinamide cofactors very rapidly (and for > 40,000 turnovers) but we are also able to monitor the process continuously in real time and make adjustments by simple interventions as required. We have already made good progress with scaling up and have demonstrated a device for the straightforward deracemization of secondary alcohols. Our work will also make it very easy to screen enzymes for desired activities, both in detail and in a fraction of the time currently required by laboratories. We have shown how we can run extended enzyme cascades with control over rate and direction with simultaneous monitoring, and are now demonstrating its application for the study of drugs that inhibit cancer-associated variant enzymes.
Sectors Agriculture

Food and Drink

Chemicals

Energy

Environment

Healthcare

Manufacturing

including Industrial Biotechology

Pharmaceuticals and Medical Biotechnology

 
Description The 'Electrochemical Leaf' (e-Leaf) is proving much more powerful than first realised. We are on track to commercialise the technology after having had a patent and more than 10 significant papers published. I have had much more help now from Oxford University Innovation, due to positive intervening by Serena de Nahlik. I am in contact with several companies and a video has been produced.
First Year Of Impact 2017
Sector Chemicals,Education,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology
Impact Types Cultural

Economic

 
Description BBSRC Follow on Fund
Amount £197,917 (GBP)
Funding ID BB/P023797/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 06/2017 
End 12/2018
 
Description Collaboration started with Professor Nick Turner, University of Manchester 
Organisation University of Manchester
Department Manchester Institute of Biotechnology MIB
Country United Kingdom 
Sector Academic/University 
PI Contribution Turner is supplying enzymes that we are using in our research. We are now writing our first joint paper, after 6 months collaboration.
Collaborator Contribution Supply of various enzymes.
Impact A grant application was submitted in October 2017 to BBSRC (Manchester and Oxford) to develop the science and technology for biocatalyst discovery.
Start Year 2017
 
Title ELECTRODES 
Description An electrode (1), the electrode (1) comprises a substrate (4, 5) on which is located a porous layer of a conducting or semi-conducting oxide (6) and having located thereon Ferredoxin NADP Reductase (FNR) (3). The electrode (1) can be used to drive organic synthesis via nicotinamide cofactor regeneration. 
IP Reference WO2017158389 
Protection Patent application published
Year Protection Granted 2017
Licensed No
Impact Discovery of a fundamentally new way of driving enzyme cascades for organic synthesis. The discovery is of value for both practical and theoretical reasons. The science is explained in a 2019 'hot' paper in Angewandte Chemie.
 
Description Invited lecture 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Invited lecture at the Gerischer-Kolb Symposium, Reisenberg Castle, Germany, October 11-13, 2017
Year(s) Of Engagement Activity 2017