Moleküler film penisilinin nasıl biçimlendiğini ortaya koyuyor

Penicillin’s antibacterial power depends on a highly strained β-lactam ring that disrupts bacterial cell-wall production, yet the fleeting stages that create this structure have resisted direct observation. Oxford-led researchers used ultrafast X-ray free-electron lasers to watch isopenicillin N synthase transform a linear peptide into penicillin’s ring system. Thousands of droplets containing oxygen-free enzyme microcrystals were placed on moving tape and carried into an oxygen-filled chamber, where the reaction began. Adjusting the tape speed determined how long each crystal reacted before an X-ray pulse captured an atomic-resolution image. Combining the snapshots produced a molecular movie under physiological temperature and pressure. It revealed a thioaldehyde intermediate just before ring formation and a one-ring β-lactam intermediate on the route to the complete scaffold. The study also showed that water molecules and subtle enzyme movements guide the chemistry. These details settle a four-decade mechanistic question and could inform the engineering of new antibiotic structures, oxygenase enzymes and catalysts.