The discovery of penicillin transformed modern medicine, but scientists have continued to investigate how nature builds the antibiotic’s essential chemical structure.
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nature → transform → structure
Researchers from the University of Oxford and international collaborators have now captured previously unseen stages in the process that produces penicillin.
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that → capture → penicillin
The team captured the reaction with ultrafast X-ray free-electron laser experiments, observing how an enzyme called isopenicillin N synthase (IPNS) converts a linear peptide substrate into the ring system that forms the core of penicillin.
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that → capture → penicillin
According to research titled ‘
Unanticipated intermediates during isopenicillin N synthase catalysis identified by time-resolved X-ray free-electron laser studies’, published in Nature Catalysis by University of Oxford-led researchers, the findings resolve a long-standing question about this complex chemical reaction.
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findings → accord → reaction
How scientists captured the hidden stages of penicillin formation
Researchers captured several stages of the reaction that forms penicillin’s structure.
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that → capture → structure
The enzyme IPNS converts a linear peptide substrate into the ring system found in penicillin.
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enzyme → convert → penicillin
Among the observed stages was a thioaldehyde intermediate, formed just before the β-lactam ring appears.
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ring → observe → stages
The team also captured a monocyclic β-lactam, the first ring-shaped structure on the path towards the penicillin scaffold.
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team → capture → scaffold
These stages had been too difficult to observe.
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stages → observe → ?
The findings provide the clearest picture yet of how IPNS assembles the penicillin scaffold and resolve a mechanistic question that had remained unanswered for more than four decades.
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that → provide → decades
How ultrafast X-ray experiments recorded the molecular movie
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experiments → record → movie
The researchers used ultrafast X-ray free-electron laser (XFEL) experiments to follow the reaction in real time, rather than relying only on static X-ray crystallographic structures.
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researchers → use → structures
They placed tiny droplets containing anaerobic enzyme microcrystals onto a moving tape measuring 2 millimetres wide.
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They → place → tape
As the tape entered a chamber filled with oxygen, the gas rapidly diffused into the crystals and started the reaction across the sample.
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gas → enter → sample
By carefully controlling the tape’s speed, the team determined how long each crystal reacted before reaching the point where it was exposed to an XFEL pulse.
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it → control → pulse
Each pulse recorded an atomic-resolution snapshot.
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pulse → record → snapshot
The researchers combined thousands of snapshots to reconstruct the reaction frame by frame, capturing intermediates that exist for only tiny fractions of a second.
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that → combine → second
Molecular movie reveals the role of water in penicillin formation
The molecular movie showed that water molecules inside the enzyme help guide the reaction.
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molecules → reveal → reaction
Subtle movements throughout IPNS help direct the chemical steps, showing that its shape and chemistry work together during penicillin formation with remarkable precision.
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shape → help → precision
The researchers could connect enzyme motion, iron chemistry, and water-mediated proton transfer by capturing structural snapshots over milliseconds to seconds of reaction time.
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researchers → connect → time
The experiments also allowed the team to observe the reaction at atomic resolution under physiological temperature and pressure.
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team → allow → temperature
These details provide a richer view of how IPNS controls a difficult chemical transformation.
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IPNS → provide → transformation
Why the findings matter for future antibiotic development
Penicillin was developed into a clinically useful antibiotic at Oxford during the Second World War by Nobel Prize-winning scientists Howard Florey and Ernst Chain, and colleagues.
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Penicillin → matter → scientists
In 1945, Oxford chemist Dorothy Hodgkin first solved penicillin’s structure using X-ray crystallography.
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Hodgkin → solve → crystallography
The study builds on that history while examining how nature constructs the antibiotic’s β-lactam ring.
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nature → build → ring
This ring interferes with bacterial cell wall synthesis, causing the wall to fail and bacteria to die.
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bacteria → interfere → synthesis
The study may also have relevance beyond antibiotics because IPNS belongs to a large family of iron-dependent oxygenase enzymes involved in human biology, including processes that allow the body to sense and respond to changes in oxygen availability.
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body → have → availability
The Aporia
