University of Oxford scientists working with Diamond Light Source’s XFEL Hub have built a frame-by-frame “molecular movie” of isopenicillin N synthase, the enzyme fungi use to forge the beta-lactam core of penicillin antibiotics, in work published in Nature Catalysis.

Using X-ray free-electron laser pulses at facilities including PAL-XFEL and SLAC, the team captured fleeting intermediates that exist for fractions of a second under high pressure — steps chemists have debated since the 1980s. The images show a thioaldehyde intermediate just before the beta-lactam ring forms and a monocyclic lactam on the way to the full penicillin scaffold.

Why the mechanism mattered

Isopenicillin N synthase performs an unusually complex transformation in a single enzyme pocket. Drug makers study it to engineer new beta-lactam compounds as antimicrobial resistance spreads. Until now, researchers inferred steps from static crystallography; the new movie ties those structures to a time sequence.

UK facilities in the chain

Diamond’s Harwell campus hosts the XFEL Hub that prepared samples and analysed data alongside Lawrence Berkeley National Laboratory teams. The collaboration underscores how UK structural biology relies on both domestic synchrotron time and overseas high-repetition XFEL beams when reactions are too fast for conventional sources.

Lead authors tied to Oxford’s Wellcome-funded programme said clearer mechanisms could inform semi-synthetic routes to new antibiotics, although any drug candidate remains years away.

What comes next

The group plans to probe mutant enzymes that stall at specific intermediates, testing whether the movie’s sequence holds when active-site residues change. For NHS antibiotic stewardship teams, the work is basic science, but it feeds the pipeline policymakers want as they push pharma to refill neglected infection portfolios.

Britain’s science budget fights dominate Westminster, yet this study is a reminder of what UK universities still deliver when beamtime, protein chemistry and international facilities align — a literal film of one of medicine’s most important molecules being built atom by atom.

Beamtime economics

XFEL experiments are expensive and queue-managed; securing time required coordination across Oxford biochemistry teams and Diamond’s hub staff. The payoff is mechanistic insight that static structures cannot provide, helping chemists design inhibitors that bind before the beta-lactam ring closes.

UKRI funding cycles favour projects with clear paths to translation, so the group will likely pursue industrial partnerships for enzyme engineering even as academic papers continue.

NHS England’s antimicrobial stewardship programmes track resistance rates in bloodstream infections; basic science on penicillin biosynthesis does not change prescribing this winter, but it keeps knowledge alive in universities when pharma companies retreat from antibiotic R&D.