Hyster establishes PLP as photoenzymatic cofactor, combining enzymes and light to unlock new reactivity

For years now, the Hyster Lab has been working on how to engage photochemistry with enzymes, relying most often on flavin-dependent enzymes. With new research in Nature last month, they demonstrate for the first time the efficacy of photoenzymatic activity using PLP-dependent enzymes.

Together with collaborators at Novartis, the lab draws pyridoxal 5’-phosphate (PLP) out of the cofactor ‘dark space’ where photoenzymatic activity has previously not been shown, opening a class of PLP-dependent enzymes to powerful bond-forming events.

Paper: Pyridoxal photoenzymes for asymmetric radical-radical cross-couplings

Journal: Nature, published July 2026

Authors: Cole Sorensen, Suhao “Tiger” Wang, Yao Ouyang, Saim Waheed, Claire Page, Greg Mann, Simon Allmendinger, and Todd Hyster.

What this is: Researchers establish PLP as a photoenzymatic cofactor by leveraging the excited state quinonoid intermediate as a potent single-electron reductant.

How they did it: In a discovery they described as “serendipitous,” the team uses two methods to bring about the success: they overcome the poor photophysical properties of the quinonoid by using non-native benzyl amine substrates; and they access the excited state with a Förster resonance energy transfer mechanism from an exogenous photosensitizer.

Their approach enables an asymmetric radical-radical cross-coupling between benzyl amines and reductive radical precursors.

Comment from P.I. Todd Hyster, Professor of Chemistry: “In this collaboration with process chemists at Novartis, our goal was to develop a way of preparing chiral amines via scaffold construction that could eventually serve as a proving ground for testing the scalability of photoenzymatic catalysis. Like many projects in my group, the linchpin is directed evolution. Its ability to systematically take low-yielding reactions and optimize them by changing the primary protein sequence is extremely powerful.

“We believe this is the first PLP-dependent photoenzyme. Others have used light with PLP-dependent enzymes, but those examples relied on exogenous photocatalysts for radical formation. We have a case where the cofactor is doing the electron transfer chemistry.

“This unique photochemistry hinged on the great postdocs and students we have at Princeton asking interesting questions and taking advantage of the incredible resources we have in this department to get the answers.”

Comment from first co-author Cole Sorensen, former postdoc, Hyster Lab; now an assistant professor at the Department of Chemistry, University of Florida: “I’m excited about this work because it opens the door to a lot of interesting reactivity. To frame this within the field, a lot of our group’s previous work has utilized flavin-dependent enzymes. It’s a design criteria that bounds how you think about accessible mechanisms.

“The significant mechanistic difference with PLP is that you need to make a covalent bond with the cofactor and substrate amine. This binding requirement presents a substantial challenge, but provides a defined substrate to engage with in your enzyme active site. Because of this, if you look through our paper, the selectivities are extremely good. This defined substrate binding is key to stabilizing a new photoexcited state and providing the correct geometry for tackling high energy radical intermediates.

“That mechanistic change allows us to think about new ways to tackle problems within the biocatalysis field. This class of enzymes is massive; it’s a huge portion of enzymes. So I think this will open a door of new types of enzymes we can look at, new types of reactivity, and change how we look at these cofactors.”

Comment first co-author Suhao “Tiger” Wang, graduate student, Hyster Lab: “PLP enzymes were not known to do this kind of chemistry before. It is known to do all the ground state chemistry, the chemistry that does not require light. And I think people have never actually thought about using photoexcited PLP cofactors like this before.

“In Todd’s lab we are also interested in pushing this PLP enzyme out of its native substrate territory. Specifically, PLP-dependent L-threonine aldolases used to only catalyze reactions on small amino acids. We started to expand this reactivity to simple amines. We’re losing this carboxylic motif, so I think that’s another achievement of this paper. We are not only expanding the PLP co-factor dark space out of this dark space, but we are also using it to catalyze reactions on non-native substrates.

“One of the challenges we overcame was in synthesizing chiral amines, because chiral amines are really prevalent in pharmaceutical molecules and also known to be extremely challenging to synthesize. You have to protect them, and it involves several steps in protection and de-protection. But for our methods here, we can get access to a lot of these chiral amines, derivatives, extremely efficiently in one step with extremely high enantio- selectivity. So it only produces one of the enantiomers, either the left hand or the right hand. That’s one of the challenges we solved.”

Comment from Associate Director of Science & Technology at Novartis, former MacMillan Lab Postdoc Simon Allmendinger, and paper co-author: “A central challenge in pharmaceutical synthesis is accessing the complex structural motifs found in biologically active molecules. Expanding the synthetic toolbox is therefore essential to address synthetic challenges in drug development.

“This collaboration was driven by the idea that combining enzymes and light could unlock new reactivity beyond established synthetic methods, creating new opportunities for the efficient and selective synthesis of complex molecules. Ultimately, advances like these have the long-term potential to streamline synthetic routes and enable more sustainable manufacturing of pharmaceutical ingredients.

“This work showcases how collaborations between academia and industry can unlock new reactivity and expand the synthetic toolbox. Most importantly, the study establishes the feasibility of a previously unexplored concept and demonstrates the value of pushing the boundaries of what enzymes and photochemistry can achieve in synthesis.”

Funding: The research reported in the journal paper was supported by Novartis and the NIH National Institute of General Medical Sciences (R35161429).