Researchers from Wuhan University and Xiamen University have made a significant breakthrough in understanding the biosynthesis of azetidine-containing pharmacophores.

This pioneering study was recently published in the esteemed journal Nature Chemistry under the title “A two-metalloenzyme cascade constructs the azetidine-containing pharmacophore”.

The collaborative team elucidated the biosynthetic pathway of polyoximic acid through a multidisciplinary approach. They discovered that the precursor L-isoleucine is catalyzed by two metalloenzymes, PolE and PolF, undergoing desaturation followed by intramolecular C-N cyclization to form polyoximic acid.

PolF exhibits "dual functionality", first recognizing L-isoleucine to form an unsaturated intermediate and then catalyzing its cyclization into polyoximic acid.

The study identified PolE as the first pterin-dependent monoiron desaturase, which precisely activates the C3-H and C4-H bonds of L-isoleucine to generate an unsaturated intermediate.

PolF, on the other hand, is a novel member of the heme-oxygenase-like diiron oxidase (HDO) family. It constructs a diiron cluster using its α1-α3 helical core. Within PolF, tryptophan residues W63, W217, and W263 serve as electron donors, facilitating the homolytic cleavage of the O-O bond to produce high-valent iron-oxo species.

This research is the first to uncover a natural molecular mechanism where natural amino acids are used as substrates in a "dehydrogenation-cyclization" cascade to construct polyoximic acid.

The role of PolE as a pterin-dependent monoiron enzyme in desaturation challenges existing paradigms, while PolF's novel intramolecular C-N cyclization expands the catalytic repertoire of the HDO family.

These findings provide a robust theoretical and practical foundation for synthetic biology approaches to azetidine pharmacophore synthesis. They also introduce new enzymatic components and scientific support for the discovery and innovative design of related drug molecules, enhancing the integration and innovative development of China's biopharmaceutical industry.