Electron Bifurcation

David Beratan: The wide-ranging sweep of skills, diversity of thought, and desire to learn from our teammates was tremendous. The integration of lessons from biochemistry, structural biology, metallo-biochemistry, electrochemistry, spectroscopy, and theory were all essential for the team's success, as dialogue had to establish across the entire team. Without any one component, plus outstanding communication and trust across the team, the project wouldn’t be where it is today.

Jonathon Yuly: I was a theorist in this team. Our role was to try to explain very complicated enzyme function using basic physical and chemical principles. It was a fantastic challenge.

Kiriko Terai: I contributed to developing the computational tools to study electron bifurcation by a many-particle transport kinetic theory.

Niven Singh: I was one of the authors of the Chem paper where I helped write the code to allow for multi electron transfer in open systems. This code has since been extended to allow for simulating other biological transport networks.

David Beratan: We have cobbled together the first comprehensive view of the essential ingredients that must be present in molecular assemblies to realise near-reversible electron bifurcation reactions with high efficiency. Our groups, and several others around the world, are now using the lessons learned by our team to design and construct the first generation of entirely synthetic biologically inspired electron bifurcation machines. These targeted systems will test the depth of our understanding and may provide a point of entry to address some of the grand challenges facing energy science today.

Jonathon Yuly: I feel this work is exciting because it provides an enticing glimpse of insight into the extremely complicated function of enzymes.

Kiriko Terai: Electron bifurcation plays a vital role in bioenergetics, including the Q cycle of respiration, nitrogen fixation, and hydrogen reduction. These reactions are of industrial interest but are very hard to accomplish by an artificial experimental set up. Nature, on the other hand, accomplish these reactions with minimal energy cost under ambient conditions. Studying electron bifurcation is exciting since it provides understandings of how these energy conversion reactions are readily achieved in nature.

Niven Singh: From the 2017 Nature Chemical Biology paper, it is the first example of getting photoexcited reduction potentials of a bifurcating system. The PNAS and Chem papers are the first theoretical papers to study electron bifurcation, inspiring further work from theory that can match experiment in the future.

David Beratan: The interdisciplinary research team has helped us resolve a mystery that has stood for about 50 years: how are short-circuiting electron transfer reactions avoided in electron bifurcating networks? These networks allow us to split apart pairs of electrons into pools of high and low energy electrons, without having to worry about energy dissipating short circuits.

Earlier considerations of the kinetic networks indicated that electrons could just fall downhill in such systems, producing heat rather than storing energy. The understanding that our team developed has revealed how short circuiting is avoided in very specific, privileged free energy landscapes. These discoveries are enabling groups around the world to build compelling efforts aimed at reproducing this behaviour in man-made systems.

Jonathon Yuly: I am very excited to see whether it is possible to build bio-inspired devices that harness some of the principles we think are at play in these enzymes.

Kiriko Terai: Understandings of the mechanisms of bioenergetics provide guidance to the development of biomimetic technologies and sustainable designs of energy generation/conversion machines.

Niven Singh: This work can serve as design principles for an artificial bifurcator. Although known bifurcating systems have inverted potentials, results from the Chem paper suggest that bifurcators can bifurcate if their redox potential ordering is highly normally ordered.

David Beratan: While real life applications are probably years off, we hope that the secrets that underpin high efficiency electron bifurcation networks will lead to new strategies to capture and interconvert energy at the molecular scale, leading to schemes to manipulate energy at lowered environmental and economic costs.

Jonathon Yuly: Real life applications are still far away, but I hope our work will lead to exciting new bioinspired devices and catalysts.  

Kiriko Terai: This work on electron bifurcation will be used in novel designs of artificial machines that accomplish reactions such as ammonia production using mechanism of nitrogen fixation by nitrogenase, and water splitting using mechanisms of hydrogen redox reactions by hydrogenase.

Niven Singh: Understanding how nature undergoes energy transduction using multiple electrons will aid in designing energy storage devices and artificial biomachines.

David Beratan: We imagine significant future developments in both theoretical and experimental aspects of electron bifurcation research in the short term, focused on both biological and synthetic electron bifurcating systems. Advances in theory and experiment promise to explain the function of much more elaborate emerging biological machines that bifurcate electrons. The lessons already learned by the team are leading to the design of synthetic electron bifurcation machinery in several groups across the globe, and we hope that future discoveries with test and refine our current understanding, as well as provide functional materials of potential value to society.

Jonathon Yuly: I think that biological electron bifurcation will continue to provide many interesting puzzles for researchers. In addition, the challenge of building a bioinspired synthetic electron bifurcating system looms large.

Kiriko Terai: The current understanding of electron bifurcation is still at a microscopic scale. The next goal will be to understand the roles and mechanisms of electron bifurcation in a single macromolecule, in a group of macromolecules, in a membrane, and in a cell.

Niven Singh: Further exploring how bifurcators can tune their redox chemistry is of great interest. Why do bifurcators have inverted potentials? And is the local environment solely the necessary driving force for redox orderings? These are some of the questions of interest to us (at Duke).

David Beratan: Our team was driven to understand the physical and biochemical underpinning of how one of nature's most central schemes for energy conversion and biocatalysts works. In addition to learning about specific examples, we were driven to develop theories, guided by experiments, to describe existing observations and to predict the outcome of yet to be imagined experiments. We also hope that the outcome of our research motivates the design of functional bio-inspired molecular structures.

Jonathon Yuly: One thing that motivated us was the astonishing function of these enzymes. They can reversibly produce low potential electrons on the molecular scale.

Kiriko Terai: Sharing ideas and discussion with team members inspire and motivate our team.

Niven Singh: Bifurcation is a process that can be viewed from an interdisciplinary standpoint (chemistry, biology, and computer science). We have people from all backgrounds in our group working on bifurcation, making it an exciting and enriching problem to work on and learn from.

David Beratan: The understanding of the emergent physical principles discovered in this project would have been impossible without the highly interdisciplinary, cooperative efforts of molecular scientists from wide-ranging sub-disciplines, and the trust and rapport that was built among the collaborators over time.

Jonathon Yuly: I think collaboration can be challenging but should be a cornerstone of modern science. The world is simply too complex for any one person to understand or even make much progress. Besides, I think that sharing science with others can be great fun!

Kiriko Terai: Complex problems in chemical sciences often require multidisciplinary approaches which can be facilitated by collaborations of researchers from different fields, perspectives, and resources. For instance, not all specialized facilities and equipment are available in one research group. Collaborations can give access to such resources and help make progress on seemingly “impossible” challenging problems.

Niven Singh: Collaboration in the chemical sciences allows researchers from different fields come together to approach the same problem from different perspectives. Collaboration allows you to perform studies where some of the experiments performed may be outside of your expertise.

David Beratan: Great research culture is based, first and foremost, on mutual respect and trust. Without these elements, free and open scientific dialogue is impossible. When many sub-disciplines are brought together to address a grand challenge, these issues take centre stage and are critical for success. To cross disciplinary boundaries, an extra level of patience, commitment to communication, and curiosity are essential. Training students in this cross-disciplinary culture has proven to be particularly fun and rewarding.

Jonathon Yuly: When I joined this project, I was completely new to biochemistry and this research topic. But I always felt welcome and that my voice was heard. I think a good research culture is built when we extend that to everyone.

Kiriko Terai: The presence of leaders who foresee both the long-term and short-term goals of a research project is very important to create a good research environment. Setting long-term goals motivates the whole team by understanding the impact and societal standpoint of the research topic. Short-term goals are essential to keep pushing actual research work toward the long-term goals. Effective team communication, which is also the role of a leader, is crucial for sharing these research goals and keep up motivation.

Niven Singh: An environment where researchers are motivated to expand their knowledge and are rigorous with their findings. A good research culture has a team leader willing to listen to the other members and receive feedback in a positive way.  

David Beratan: The challenges faced at the global scale, surrounding the availability of clean water, food, energy, and medicines, all have molecular solutions. Contributions from every single sub-discipline of chemistry will be required to address these tremendous challenges, and serious efforts to meet these profound challenges are creating compelling new scientific opportunities.

Jonathon Yuly: Chemistry describes so much of what is around us, from what holds living cells together to why iron rusts (and how rusting can be reversed!).  

Kiriko Terai: Chemistry is a branch of natural sciences that allows us to understand the behaviours, properties, and structures of matter by addressing how properties of electrons, atoms, molecules, etc. that make up matter change during reaction with other matters. Since chemical reactions are central to many processes that occur in nature, chemistry helps us build foundational understandings of the world around us. Chemistry has provided us understandings of “how things work”, and thus, are the foundations of the advancements of medical treatment, electronics, sustainable energies, etc.

Niven Singh: Chemistry helps us understand the world around us that we cannot see. It is an integral part of our lives, and this understanding grows everyday as more studies are performed.

David Beratan: Focus on interacting with other scientists who are passionate about what they are doing, are challenging themselves to understand the world, and wish to elevate the entire enterprise of chemistry and discovery. If you are excited about your research, and you are surrounded by similarly motivated colleagues, great things will happen!

Jonathon Yuly: Take risks and think big!

Kiriko Terai: Working in chemistry research takes you to the edge of human knowledge and pushes you through the boundary (upper limit of human knowledge). You should be proud of how your effort can expand human knowledge, but at the same time, it is important to be aware that the advancements you make are infinitesimal relative to whole human knowledge.

Niven Singh: Do research in both experimental and computational chemistry to see if you enjoy both and/or either. Talk to professors and students to find a topic that may be of interest to you and if given the opportunity, perform independent research. Once you struggle you will be forced to problem solve and that’s where the personal and scientific growth will happen.