Native chemical ligation isn’t just for building big peptides anymore.The reaction, which forms amide bonds in water without enzymes, has also been used to construct nucleic acids. Now, chemists have shown that the ligation can even generate phospholipids, which then spontaneously form vesicles about the size of a skin cell (Angew. Chem. Int. Ed. 2014, DOI: 10.1002/anie.201408538). Enzymes in nature make phospholipids with thioester precursors, and native chemical ligation also involves thioesters—it forms amide bonds by coupling them with a terminal cysteine amino acid. So Neal K. Devaraj and colleagues at the University of California, San Diego, adapted native chemical ligation to make phospholipids nearly identical to those in nature. Phospholipids have been challenging to assemble in a biological milieu because precursors are insoluble in water or require catalysts for assembly. Devaraj’s coworkers, Roberto J. Brea and Christian M. Cole, demonstrated that their ligated phospholipids form within minutes in water at neutral pH and then self-assemble into vesicles. The researchers encapsulated green fluorescent protein in their vesicles, and they suggest that their approach could be used to construct liposomal drug delivery systems.
Native chemical ligation reaction sequence builds synthetic phospholipids.Native chemical ligation reaction sequence builds synthetic phospholipids.
Angew. Chem. Int. Ed.